Sometime Never: A Fable for Supermen, by Roahl Dahl
The Earth Abides, by George Stewart. Story is set in Berkeley, CA after a disease kills most life on earth, maybe a little too on the nose these days...
Paolo Bacigalupi's short stories (e.g. Pump Six), some of which he later turned into longer books.
Courtship Rite, by Don Kingsbury. Plot is kind of bland but the worldbuilding is fantastic, essentially an attempt to create a world where cannibalism isn't immediately though of as an ultimate evil, which leads to odd implications for society.