One of my gripes about the game is that there's little incentive to play "hisotrically." As Rome I never bother taking Gaul until after Greece or Egypt,since they're poor heathen barbarians, and liable tor revolt.
I'd strongly suggest looking at the basics assimilation and happiness mechanics to make "Romanizing" Gaul more worthwhile- tribesmen shouldnt really care about AE Imho, and should assimilate more quickly. The citizenship mechanics would overlap nicely with this, since presumably it will be much harder to just romanize Greece.
I'd also suggest allowing trespassing on tribal lands to allow historical panic wars, both Hannibal and Rome crossed freely between the southern goulash tribes (Hannibal even fought with several of the on the way to invsding itqly). Fighting Carthage is a PITA since you can't walk to Hispania nor really gain sea dominance (and if you've got control over the waves why not go for Carthage itself).
