Mervyn Peake - Gormenghast (and sequels). HARD to get into, but rewarding if you understand that they are very experimental.
F.M.Busby - The Demu Trilogy. Nothing ground-breaking, but it is well written escapist fiction.
James Blish - Cities in Flight. Ditto the previous.
John Crowley - Little, Big. Please please please DO read this. It is the single best book in the English language. Each chapter is like a gem. Another of his books "Engine Summer" is also jaw-droppingly lovely and has a "reveal" at the end that makes M.Night Shamylam seem like a moron. You WILL weep unashamedly. His later stuff is hard to digest, but worth the read if you stick with it.
Lin Carter - The Martian books (The Valley Where Time Stood Still, The City Outside the World, Down to a Sunless Sea, and The Man Who Loved Mars). Thinking man's pulp fiction.
James H. Schmitz - The Witches of Karres. So fun to read. It's a novelization of a series of short stories (or it reads that way, anyway) concerning a trio of underage witches and the space captain they "adopt" and whose life they make miserable but in a good way.
Apologies for spelling/grammar/mispronunciation/