One click insta-armies seem too simple. I wonder if there will be more to producing a fighting force in CK2. Lord knows it wasn't that easy to get the filthy peasants to fight for you way back then.
I would like to see manorism with feudal retainers. You manage your resources which limits your troops and the land can sustain so many. Similar to troop movement in EU III and active demesne limits based on provincial decisions. Also has a muster time limit. E.G you call for your troops they will muster in x days. You summoned a vassel to your court he will arrive in x days. That sort of thing
That sounds like a good idea. You should also have a small contingent of men on hand that you can call up for smaller missions like putting down little rebellions, etc.
you mean an armed retinue. In England during the Stuarts or earlier (post Bosworth Field) they had the King's Gentelman Retinue or Lifeguards.
However during the middle ages they would like just be Men at Arms or Knights. Likely part of the Household. I suppose you could count a character as either having their own household which moved with them or being attached to another's household. When in residence or a region the household could be set to "take up arms" or to "hold court" Meaning that direct military use has to be intended and not spur of the moment.
A long time ago I suggested that the types of recruitment should be a decision type process (like with laws in CK1)
Say you could have 4 types of recruitment.
Levee en masse/feudal system: Just your average call to arms to all vassals. Can be modified when certain technology is unlocked/researched.
Semi-professional: Feudal system supplemented to hirable/standing troops. this means you can actually hire the amount of troop you want and need, and it would resemble EUIII and most paradox games, however you can also call to arms your vassals to supplement your force.
Professional: Fully professional force, regularly paid. Achievable only after certain technology is unlocked. No call to arms from vassals.
Tribal(?): This is more of a maybe. A special type of levee en masse for nomadic cultures, which generates slightly more troops and predominantly cavalry. A special feature about it should be that if it faces another tribal army it absorbs the previous one(just an idea to represent the Golden Horde).
I believe that you should have a professional core to your army (your own retainers and those of your closest vassals + mercenaries). You can then call levies (of militia) in particular regions. Finally, in case of invasion, a full mobilization.