You probably remember that I had some scratched of tech tree for the CW! I've for a long time been playing around with an idea of making a real tech tree, instead of the linear tech branches of DH. If you want, I can use these ideas for CW!
Some of my ideas:
* The amount of available technologies grows--at first, the tree is narrow, but after researching some important 'root' techs there comes a growing number of options, some of which lock other options.
* Tanks come in play rather late, so there's some need for cavalry too.
* Player can specialize by developing improvements instead of just new models.
* To boost the progress in smaller nations, some technologies may give free IC and money, instead of just plain percentual bonuses which clearly benefits large nations more than the small nations.
As for the map, as there's no need to keep on historical borders, I suggest making every province roughly of the same size and shape. If every province borders six other provinces (of course there must be exceptions, especially on the coast), the warfare becomes more interesting and realistic as there can be no exploits.