Have you ever tried the Gormenghast books by Mervyn Peake?
Very different than LOTR, but, similarly, it describes a world that takes on a life of it's own. Lots of dark characters, all human, with all the action taking place in an endless castle that's a character itself.
If you're in the mood for something light-hearted, there's always the Discworld novels by SIr Terry Pratchett. They lovingly parody every fantasy cliche, while building a world that stands on it's own as a unique creation.