Two features I would like to see in the future are:

-The ability to set the difficulty levels for each "human" player separately, as well as for AI players. For example, when I join a game with my friends a few of them have no/little experience in GalCiv and therefore fall behind while I pull ahead. If I dumb down the AI the game is too easy for me, if I increase the AI the game is too hard for them, same goes for player on player battles. If I could boost my difficulty separately, or make it easier for them, we could all compete on a level playing field. 

-Simultaneous Multiplayer similar to the way it was implemented in Civ IV (And many other recent 4x games). The turns just take too long if everyone has to go sequentially and can lead to very long, boring games with other "human" players.