Hmmm, lots of good taste round here! I'll second Frank Herbert (although as Col says the later Dune stuff kind of loses it), John Brunner and Philip K.Dick are also both excellent choices.
some more Philip K.Dick recommendations:
The 3 stigmata of Palmer Eldritch
Do Androids dream of Electric Sheep
A Scanner Darkly
The Man in the High Castle
The Divine Invasion
Flow my Tears the Policeman cried
I have another recomendation from an author you might be surprised by... Doris Lessing's 'Canopus In Argos:Archives' novel cycle. The style changes wildly between novels but I'd say 3/5 of them are absolute classics. The first one is 're:colonised planet 5, Shikasta' and is written as a series of documents by an interplanetry/interdimensional being over a period of 20,000 years. Highly recommended
anarres, when you
eventually come visit the south coast I can lend you about half the books in this thread
