You know, some planets (like Jupiter), the moon is more habitable than the planet is.
Yeah, but in that case you would have to set up a
colony, not a "mining base."
Habitable is great for colonies, but it comes with significant costs and complications that asteroids don't have: gravity, weather, wildlife, magnetic fields, laws, conservationists, taxes, etc. If you want to colonize major moons, ask for that as a separate request.

for the gas giants i was thinking more of an orbital facility then a "floating" base. i would basically just like to see all these useless objects in the game be used for somthing.... anything... it would give the game some more depth. some might call it useless clutter, but i like the idea.
That would then basically be a "research starbase" or a "manufacturing starbase," wouldn't it?