I'd personally like to see a little more variety in the existing planets, especially gas giants [they all look like Jupiter
]. The gas giants should also be significantly larger. I'd also like to see the sun surface view range decreased a whole lot so that you have to be in the gravity well of the sun essentially to see the surface of it... Otherwise just bloom light, would look better. Stars look kind of like large molten planets when you zoom in, they lose their shine. An ability to terraform would also be semi-wooty.
Also:
Probably hard to do, but skins of a planet that change when they're being bombarded... "Burning Terran planet", "Glassy Desert Planet", "Melted Ice Planet / Water world"... kind of a temp effect... but would be a nice piece of eye candy 
-DrGonzo