Will all the strategy games out there there has always been some sort of capital, but when u have a solar empire that spans STAR SYSTEMS there is going to be a VERY large need for red tape With alliance going to play a big part in late game play if you have control of the majority of planets in the system it would be nice to have a "capital" other then ur home planet, that would also be able to take control of the rest of ur planets should ur home planet be disable (bombed to the stone age), THis would also give some sort of allegiance bonus because once u start to get 4 and 5 jumps ratings take a nose dive with 100% culture only a adding a 10% bonus this makes planets had to control when ur neghbor is also doing the same thing. the interesting thing to do would be to make the capitals like states that could rebel if they felt strongly enough about leaving jsut liek with the various tech insurgents.

just a suggestion but maybe worth exploring