Spread about, normally. There would be sphereworlds thrown about the map, probably with lost components and ruins on them.
Essentially, to create the individual nations, all that would be needed to do (roughly) is to replace species portraits with a large flag, and some name changes (Emporer, titles, etc). For instance, the UN holdouts that survive the destruction of Earth, specifically a Martian colony, would be filled with different citizens, at least one million from each nation.
I've also noticed that there are very few scenarios/maps out, especially ones that deal with our solar system.
BTW, you guys rock.
