I reread Finnegans Wake and Don Quixote every couple years.
EDIT: and I have to admit to an odd attraction to and repeated returns to reading Henry Fielding's The History of Tom Jones, a Foundling
Update: Great, thanks for the suggestion - I'll go look it up at the uni library.
Non-fiction: stuff about military strategy (Sun Tzu, Clausewitz; musashi - the book of 5 rings). Philosophy (zen, taoism; epistemology and philosophical logic). Mathematics.
+ stuff on TODO-list that I have to catch up with.
"Lord of the Rings" J.R.R.Tolkien
"The Last Wish", "The Sword of Destiny" A.Sapkowski
"The Last Unicorn" P.Beagle
almost anything by S.Lem.
My favorite mainstream book is
"Wielki Las" Zbigniew Nienacki (unfortunately no English translation available).
Anything by Terry Pratchett