Pop cap in GC and space stations
This is really a simple idea; ATM a planet gives you a pop cap of 5 in galactic mode while the pop cap a space station gives is 10-12-13-...( I think), almost forcing you to build a space station above every single planet you have, because a planet alone won't even give you the pop cap needed to properly defend it, let alone build a fleet or attack force.
I would suggest increasing the pop cap of planets pretty heavily, perhaps to 10 or 12, while decreasing the pop cap a space station gives to e.g. 3-6-8-10-12 (or similar) and increasing its prize (especially on the lower levels), perhaps to 1200-1800-2400-4800-6000 (from 600-1200-2400-4800-6000).
That way, building a space station would become more of a strategic decision (because of the higher prize) and would be less needed just to up your pop cap. ATM it is normal to have a level 1-2 station above every single planet - that is neither movie-like nor strategically interesting.
I'd find it perfect if space stations would be similar to Turbolaser towers, built as a heavy protection of a strategically important planet or above a central planet as a space factory rather than being more common than a barracks....