I know you guys already have a long list of things to do, but.....
For the Earth Map:
The one thing I miss about Rhye's and Fall of Civilization (I was waiting for a CTD patch) was the CityNameManager. The game choses city names based on location and founding civ. If a city was conquered, the city name changed accordingly.
Egyptian "Aarru-Hetep" = Arab "Urshalim" = Greek "Ierusalim" =
Persian "Yerushalayim" = Roman "Aelia Capitolina" = Turkish "Kudüs"
Carthaginian "Ziz" = Roman "Panormus" = Greek "Panormos" =
Arab "Balharm" = French "Palermo"
Yes, I can name my own cities correctly, but I would have to into WorldBuilder to change the AI's names. But then you cannot avoid cheating, learning stuff you wouldn't otherwise know.
I think it would add to "realism" to explore foreign territories and have cities where they are "supposed to be."