I'm just starting 'properly' with VSF, instead of having it as an occassional location for time-travellers from other settings, and perhaps because of this I have a bit of a whacky take on it, but I like Atlantis as a setting. Nautili, Aeronefs, strange energy weapons, martians, dinosaurs, and oodles of mad scientists making crazy devices, in any kind of topography you like - deserts, mountains, swamps, jungles, cities (both inhaboted and ruined)... what could possibly go wrong?