...what VSF planets would you conjure up?
My friend Eli and I have been discussing this topic privately by email, but its such an interesting idea that I thought it deserved a mention here.
Some of the ideas so far - note that all need a good deal of PSB* to justify:
Jupiter or Saturn
Living in floating bubbles in the atmosphere, mining the rings, processing gasses out of the atmosphere, etc. Floating cities, flying vehicles. Make the Great Red Spot a creature rather than a storm... scary stuff if it notices Jupiter's newest inhabitants.
Ganymede, for instance. Heat from the gas giant makes the planet terrestrial.
Inhabitable, but only barely, possibly along the twilight line. A place of extreme vulcanism, its mineral wealth is undeniable. Perhaps used as a prison planet? Think Mustafar from Star Wars Episode III or that prison planet on Chronicles of Riddick - can't recall the planetary name. Inferno, perhaps?
Stargate-style travel to extra-solar planets. One way stargates even more fun, as the pioneers would be forced to first build a return gate before they could come home. Good roleplay potential there, at any rate...
Hollow Earth, either Pellucidar style (dig your own tunnel through Earth's crust to get there) or via tunnel at the North Pole to Skartaris (courtesy of DC's The Warlord comic book, which is supposed to be back in publication!).
Lots of possibilities out there... share some of your ideas!
*PSB: Pseudo-scientific bulls**t.