I took this (and added to it) from the "build your own division" thread.
[All of the ideas listed here are not mine; some i have gathered from others on this thread.]
Hellfish6, I just wanted to mention that you have done an INCREDIBLE job in this thread, and that your ideas are some of the best i've read on the subject. The battalion concept is one that i've thought of in the past, and i agree that it's the best option for HOI3, if it actually comes out. I mean, how many times have you wanted to garrison (or just have a presense) in a province, and you have no choice but to send a 10,000 man division to do it? It's more realistic to overstrength you units on the front line at the expense of having smaller, 4-6 battalion divisions in the interior. Smaller units are, in my opinion, a better choice for island fighting, and in regions with few troops, to increase outflanking manuevers.
Furthermore, as most people here have pretty strong opinions for staying with the division/brigade system OR changing to battallion-sized created units, i feel its necessary to point out that
using a template to create divisions (for example, with war between Germany/USSR) production would work out almost exactly like HOI2 and using the battallion editor would simply help out for small-corps sized units engaged at other, more constricted locations (islands, N. Africa, jungles of SE Asia) where large Armies were not feasible or effective. In essense, it makes small battles between 2 divisions as interesting as the large battle with 100's of thousands of men.
Someone on the first page of this thread mentioned Master of Orion (by which im pretty sure he meant MOO2, not 1) as a good idea for the ship/division upgrade template. In master of orion 2, you could take any ship at any time, and either upgrade it piece by piece or upgrade it with one of 5 presaved templates. Even though you could have stack of 20-60 or so ships, the upgrading wasn't tedious; in fact, it was half the fun of the game, to see how the millions of different combinations would affect unit vs. unit combat. I think its a great system to model in HOI3; clean, quick (if you want it to be), and in-depth (if you want it to be).
I also liked the idea of a casualty counter that someone mentioned a few pages back; the ships count how many ships they sink, and this would give an equivilant to the land units in general, let you know overall how your war effort is going--maybe it could even effect recruitment? (maybe more desertion if your getting killed at a 10-1 clip?).
Different types of CAG on carriers (and differing capacity on fleet AND escort CV) is also an awesome idea, as you can differentiate mission types (purly sub hunting, fleet destruction, fleet protection, etc).
Also, one of the best other ideas i heard here is the SMG, or assault battallions, for urban fighting (especially with the "Urban" provinces). Similarily, the siege artillery battallions is a great idea too, for heavliy fortified provinces like Moscow and Maginot line provinces, since there really isn't a good antidote to places like that unless you bring in 60 divisions or so from about 40 different directions.
Here are some other ideas that i would like factored into HOI3.
1. I think that the player should be able to concentrate his forces at each territory junction with adjacent provinces, not in the territory at large. I say this because provinces are themselves huge. Strategic chokepoints (i.e., borders with river crossings, or mountain/mountain borders) could be manned with fewer divisions, and expected routes of attack can be defended by more divisions, etc. Major strategic bridges over the major (i.e., Nile, Rhine, Danube, Volga, etc.) should be included. Yes, this would be a Unbelieveably HUGE change, but i think it would add to realism (basically breaking down each province into smaller areas where you can choose to garrison your troops). I give this as an alternative to those who say there should be NO provinces, simply points on a map (cities, factories, AA, etc.); i think offering MORE provinces is a good compromise with people that want TOTOAL tactical freedom and those that see realistic limits to what processers can do. Also of note is many provinces could be effectively argued to have 2 distinct terrain types; having more quantity simply makes the globe/map more realistic.
2. I think POW's should be factored in. If you encircle and destory 10 Soviet infantry divisions, the men do not simply dissappear; eliminating them takes prodigious ammounts of ammunition, as does feeding them. POW camps should be constructed at the provincial level and supplied (.2 or whatever/day per 10,000 men); failure to do so raises partisian levels in captured territories and increases your beligerance, inciting more powers to conspire against you.
3. coastal batteries should engage passing enemy ships, with limited effectiveness in open seas (island coasts) and more effectiveness in constricted passages (Bosperous, English Channel, ect.) . Conversely, ships offshore of an unfortified enemy coast should slowly reduce its infrastructure or sea defenses (constant bombardment).
4. Tech teams should be based in a (historical?) province, and if that province is captured, all research is lost. Research can be handicapped by strategic bombing of said province.
The quality of a produced combat unit should depend on the quality of the tech team. Nation-specific technologies should/could be factored into National tech trees. Tech teams should have a percentage chance of being captured by invading armies that occupy their historical province (i.e. become selectable by conquoring nation).
5. Partisian units operating in captured territory should be able to be "funded" or supplied by the host nation (as a bonus, not a requirement) and additionally be constructed (cheaply) and infiltrated into position.
6. New construction options (seperate from the general "land fortifications"): Hardened sub pens (protect reconstitution of submarine units) and Underground factories (to protect IC production). These have historical precedents.
7. Allies (in Single player) should be able to communicate with each other regarding attacks! If my forces are attacking an enemy provinces, i should at least be able to allert my allied forces in adjacent provinces to attack at the same time.
8. Having an idle engineering battalion (or more) in a province already conducting an upgrade (i.e., infrastructure improvement, land fort construction, airfield, etc.) should decrease the amount of time it takes to complete, though it would result in their organization not increasing.
9. In a manner similar to naval combat, land divisions could have different engagement ranges (accounting for the longer reach of heavy artillery and siege weapons) where they could sit just beyond the reach of defenders and
force them to sally forth or be pummeled piece by piece. This ideas was proposed a while back by someone else, and i really think it could work in both provinceless configurations and in the smaller provinces that i advocate. I like the idea of having an "artillery barage" command in conjunction with the regular attack support attack reserve commands.
10. Also, as regards more, smaller provinces (which, by the way, would reduce the monsterous stacks of 40 fighting 40 divisions that never really happened in WW2 because
more provinces = more places to hold the line), i think there need to be a few more Urban areas, Rome, Paris, Rio, etc., not because i think there needs to be more urban combat, but becuase these cities are MASSIVE, even in 1940. Even Birmingham (US), represented in HOI2 as a forest, was in 1940 a large industrial city of 250K and was the second largest producer of steel in the country (incidentally its where im from). True, most of the province in the game is forest and hills, but the city itself should be a urban tile, as should some other choice locations.
11. I think i can universally say that the US AI putting 60 divisions on Guam should be fixed

. I also think there should be a max capacity for some islands, especially small S Pacific islands with limited water resources.
12. In keeping with the idea for different sections for provinces, i think defensive fortifications should be drawn up for certain borders, not all of them simutaneously. Also reduce its construction time and cost (?) AA should be concentrated in a sector of the province too.
13. Someone else mentioned combining and/or superimposing the attack/defense progress meter with a graphical representation of the province. This sounds reasonable to me, even with currrent programming and computer limits.
14. I agree with the popular notion that the game length should be extended slightly, probably 1931-1950 or 1956, with an option to continue beyond that date with no score recorded.
15. I also agree with earlier proposals of more control allowed for puppets and allies. I believe puppets should have their production, land improvements, and leaders manipulated by their masters. As i mentioned earlier, allies should be allowed (or at least invited, or notified) of attacks occuring in adjacent sectors.
16. I highly recommend an earlier thread where overlapping Roa's were employed on a gradient, where slight overlap indicated recon skirmishes, and more thorough overlap indicated heavy involvement, with the respective increase in % effectiveness. This is a BRILLIANT idea, as are most of his other ideas on gradiants (pop migration, partisian activity, etc.).
17. There was another good idea posted earlier that i dont think got enough attentions, especially in a game where pretty much all nations had drafted armies--the idea of categorizing divisions (or battillions) as rated A/B/C. "C" rated formations, made of old men and extremely young boys with sub-par equiment, would be cheaper to maintain, have a permanently lower (capped) organization, slower to move, but produced quickly to fill gaps in the line.
18. Not far back in this thread, someone explained why the current HOI2 system of infrastructure/IC destruction following conquest (usually 1/2) is unrealistic (i.e., when 4 armored divisions quickly rout a single infantry division in 1 hour and still 50% infrastructure is destroyed), whereas constant combat in a province for months results in the same destruction. A definite revision of this, i think, is necessary.
19. On a personal note, I find it would enhance gameplay if a small weather icon were placed somewhere in the province box so that i can more quickly see the current weather conditions.
20. Amphibious operations should be increasingly allowed (in additional territories) as new amphibious techs are researched, and as their corresponding attached battillions (LST's and other landing craft) are produced and attached properly. Landing/assault craft should be attachments to Transport flotillas, and should enable "amphibious assault" type missions; otherwise, transports are only useful for transporting friendly units between friendly provinces. Also, as regards the "new" province system, a province should have a "beachhead" or "coastal" "Territory," where battillions must be placed to oppose a landing (perhaps a new terrain type altogether, where defensive modifiers are nonexistant).
21. Consumer/civilian technologies? Perhaps you could assign one of your tech team slots to research things like "advanced economical passenger car" that teams such as Volkswagen and Ford woud excell at, the result being a lowering of dissent in your territories?
In any case, these are my thoughts. I also want to put my two cents in (again) in regards to the whole battallion and micromanagement thing--like someone said earlier, what else do you really do 1936-1939 anyway? When i plan to play a game of HOI2, i give myself weeks and sometimes more to complete a game. Personally, i want it as realistic and detailed as possible, within reason; if you want to make allowances for casual gamers, fine, let them play HOI2, but I think HOI 3 should be designed for the hard-core gamers that have supported this type of game for decades.
Furthermore, if everyone here could decide (or vote) on a universal list of recommendations for Paradox, does anyone think that would help matters any? I would really like to see HOI3 come out, and I would like to do whatever i can to make that happen.
(I will continue to modify and add ideas to this post as i scour the threads on this site and collect them here, as a handy reference page)