That sounds like the Rain Wilds from her Liveship Traders and Dragonkeepers series. They lived in the trees because the ground was flooded or semi-flooded all year round. They also were changed by the environment…they grew wattles and scales and such, which is explained in later books.
For instance, Jasper fforde’s Shades of Grey* has a fascinating SF world where society is rigidly structured based upon what colors you can see. It also a weird post-apocalyptic one that has strange rules like a ban on the manufacture of spoons and where Lincoln green (the color itself) is a narcotic.
fforde’s Thursday Next novels also have some very strange world building.
There’s always the Dyson Sphere, written about by many authors (such as bob Shaw, in Orbitsville and Orbitsville Departure) – bigger than Ringworld, but requires artificial gravity. The problem is that it’s so damned big, no one can really do it justice. Even after introducing it, most authors then blissfully ignore it.
Terry Pratchett’s Discworld, of course
and the O’Neill L-5 Space Colonies (and other such colonies)
I am blanking on the title or author but I read a Fantasy book years ago that had worlds based on the four elements: Earth, Air, Fire and Water and one thing I found interesting was rather than making the Fire world a cliched Volcano and Lava filled place, it was an unbearably hot steamy Jungle World. I thought that was a creative take on it.
The setting of Brave New World was also one of my favorites. A Dystopia that is insidious because plenty of people wouldn’t even agree it was a Dystopia.
Piers Anthony is apparently an awful person and the book quality sank very quickly but I always enjoyed the setting of the first three Apprentice Adept books. The Game on Proton was very cool and the way Magic was presented in Phaze was interesting (Each Adept having a Color and Style of Magic).
The Star Trek Novels’ take on the Breen is inspired. It is essentially a mini Federation that has taken Equality and Meritocracy to extremes. The member races are all forced to wear those helmeted uniforms even though only one of the races actually requires them so that everyone is the same and on equal footing.
I liked the deity set-up in the Weiss & Hickman Rose of the Prophet trilogy. Each taking their facet on the jewel and deciding how to assign their immortals and how those decisions affected their mortal followers, etc.
There was a 1998 made-for-TV movie version of the book which I thought was pretty good, I even liked the changes they made to make it more cinematic.
As for awesomely creative I’m not sure if The Culture by Iain M Banks would merit that description in an overall sense (its actually fairly standard aliens and spaceships at its core) but as he openly admitted himself he was all about the ‘gee-whiz, that’s neat!’ details and at that he excelled.
In the latest (and last) Culture novel he depicted a heavily fortified moon that had been gradually lowered until it was orbiting in a massive channel below the surface level of the planet. :eek:
Both Charles Sheffield, in The Web Between the Worlds, and Hal Clement, in Raindrop describe an artificial earth satellite that’s basically a sphere of water with a tough retaining skin on the outside.
Mervyn Peake’s Titus Groan novels and James Stoddard’s The High House both have a world contained entirely within a building. I like the later better for its imagination: dinosaurs in the attic, tigers and carnivorous furniture in the basement, oceans inside rooms, and so forth.