I don't do a whole lot of re-reading myself. There's so much reading and writing I want to get done that returning to a single book or a set of books doesn't cross my mind. The Chronicles of Narnia (the whole set) would be the exception.
Now, my daughter, aptly nicknamed Chipmunk though she's grown and her face has slimmed, is stuck in a circle of Diary of a Wimpy Kid. I can't get her to another book, or set of books, no matter how hard I try. Pretty soon, she's sure to have each book memorized, word-for-word. I try not to complain since she IS reading, but I would love for her to expand her reading choices.
I mention all this because I'm interested in what folks find themselves re-reading. What brings you back to a certain book?