I wonder if Arcadia in Skies of Arcadia was based on Venus. Venus, of course, is a very toxic planet with extreme pressure and temperatures, but that's not the case for the whole atmosphere. The upper atmosphere is actually reasonably habitable, with about .9x the gravity of Earth, similar atmospheric pressure to Earth's Troposphere, and a survivable climate. The only issues are being restricted to living in the sky, and a lack of breathable air.
In Skies of Arcadia, you even