Strange is the night where black stars rise,
And strange moons circle through the skies,
But stranger still is
Superman's home planet is pretty weird. Weird enough that it makes a good substitute for Carcosa in McKinney's supplement. You can keep the polychromatic humanity (that might explain the Krytonian flag). Then, check out the maps of Krypton for places to visit:
The highlights there ought to be pretty obvious, but let me fill in a couple of salient points of adventure and/or danger:
Jewel Mountains: Formed by the accumulated carcasses of prehistoric, giant crystal birds.
Gold Volcano: It should be mentioned that gold is so common on Krypton as to not be particularly valuable.
Fire Falls: A fall of a fiery fluid from the planets core, inhabited by mutant fish-snakes whose bite is poisonous.
Scarlet Jungle: An expanse of forest in red and purple, including huge maroon mushroom-like growth. It home to at least some disease-causing spores. Then, of course, there's the herd migratory, vaguely humanoid-shaped plants.