Originally Posted by
cannon_fodder
Simulatenous turns, aka WEGO. Forces you to predict your enemies' immediate actions, could lead to a greater diversity of battles, eliminates arbitrary turn-order advantages, and makes multiplayer campaigns practical (not that I think CA should design for that, but the hooks and functionality should be there for modders). Also opens up the possibility of coordinated attacks with your allies, assuming of course the alliances are actually meaningful.
Greater emphasis on supply of your armies. Hasn't that been one of the most important aspects of war for thousands of years? Also related, reinforcement that can be done in-place. You shouldn't have to move a unit back to a training ground to replenish it.
A tighther focus, as in Shogun.