[Theaetetus]

If you want thing with thematic and philo stuff Tom Robbins provides a lot. I highly recommend Skinny Legs and All, Fierce Invalids Home From Hot Climates, and Still Life From Woodpecker. His style is unique to say the least.

If you are looking for things more along the lines of 1984, The Disspossessed by Ursula LeGuin, and The Handmaid's Tale by Margret Atwood are both awesome.