What is your purpose in reading SF?
Do you want to be better able to understand the sort of references someone on Less Wrong might make?
Then I'd suggest The Moon is a Harsh Mistress, A Fire Upon the Deep and Accelerondo.
Do you want to be exposed to a lot of futurism ideas?
Then I'd suggest Permutation City, Blindsight and Rainbows End.
Do you want to read something that's just fun?
Then I'd suggest A Civil Campaign, On Basilisk Station and Ender's Game.
All of these books are written by people who have written multiple books, if you find you like them, you can easily read their other titles.
I have never read very much Science Fiction, unlike some of the people here on Less Wrong, and I think I would like to. At least, the few books I have read I enjoyed. I've read a couple of books from Asimov's Foundation Series, two Michael Crichton books, Twenty Thousand Leagues Under the Sea by Jules Verne, and an anthology of SciFi short stories (no really famous authors) that my dad owned.
That list looks very short. I just finished reading a fiction book, and am looking to start another. Recommendations? What are the two or three books I simply must read?