Pre 1980? hmm... Best book I've ever read is "I who have never known men" - don't be fooled, this is not some kind of feminist lit. Futuristic, and very deep-also short.
Brave New World - fantastic, also futuristic
Watership down- fantasy - about a rabbits - but not childish
To Kill a Mocking Bird
I have been reading Vonnegut. They're entertaining so far. Ray Bradbury, 70's era Crichton (I found an old paperback of The Andromeda Strain with cigarette ads in the middle. :b), and Camus are authors I've liked at least a little. I'm enjoying Snow Crash from 92, which I'm reading now, if you haven't read it before.