As a teenager, I read ALL of Sharon Creech's books. Well, all that were around at the time anyways, she's probably come out with more since "my time". Then there's other young adult classics I fell in love with like "The Giver" and the subsequent two books, "Gathering Blue" and "Messenger" (Lois Lowry). I just read there was a fourth one out in 2012, called "Son" and now I'm curious to read that. I read a lot of Anne Rice too at the time. Would be interesting to read it again.
I'm a big fan of Neil Gaiman.
I read so many great books in college that I want to re-read but don't come to the top of my head now (those were chaotic years). One being White Noise by Don Delillo.
Crime and Punishment by Fyodor Dostoyevsky is a favorite too.
Life of Pi by Yann Martel.
Nausea by Jean-Paul Sartre.
The Stranger by Albert Camus.
MmmmMMmmm....So many good books, it's unfortunately hard to remember them all at once.
Edit, I read a few of the books mentioned above that I also loved, "Go Ask Alice", "Poisonwood Bible" and of course "1984", "Brave New World", "House of Leaves".
Oh it wasn't mentioned, but I quite loved "Atonement" by Ian McEwan and I forgot that I intended to read more of his books. Well, now I'm remember more stuff I enjoyed, "Wuthering Heights" by Emily Bronte (that took me a good third way into the book to start really understading and thus enjoying it). OH OH! How could I forget! I fucking LOVED "Infinite Jest" by David Foster Wallace. Goddamn was that book a trip.
Hermman Hesse's "Siddharta" and especially "Steppenwolfe"