I know nothing has been mentioned about this yet regarding fleet starbases but one of the features I'm would like to see are some sort of personal quaters. It'll be nice to have general areas where the fleet member can use the bank, exchange and so on, but it would also be nice to allow fleet members to have their own personal area on the starbase. I think this would give them a more personal reason to work towards improving the fleet base. Judging by the size of the bases in the screen shots this could also be tied into the bigger the base the more room there is for this sort of thing.
I also think you could tie this into the idea that the more a fleet member works withing the fleet to get promoted (and contribute to the fleet) the better their quaters would become.
I know some people are going to argue that this peanalizes the casual player again, but I know in our fleet anyway most of the lower members understand that if they don't have a lot of time to play they won't make it into the officer ranks, but they still enjoy being able to play with the fleet when they are online.
Anyway it's definitely a feature some of us have talked about and really hope Cryptic will implement either with season six or down the road.