Here's a short chunk of Rereading Barthes and Nabokov, from Zadie Smith's collection of "occasional essays" Changing My Mind. Her exploration of the topic gets a lot more involved than this excerpt implies. Buy the book, read the essay. But first, here's this passage I just love. Maybe because it agrees with my experience as an avid rereader so well, and stands in elegant and poetic defiance of the standard rejection of rereading books I've heard from so many people.
Curiously enough, one cannot read a book: one can only reread it. A good reader, a major reader, an active and creative reader is a rereader. - Vladimir Nabakov, "Good Readers and Writers"
The novels we know best have an architecture. Not only a door going in and another leading out, but rooms, hallways, stairs, little gardens front and back, trapdoors, hidden passageways, et cetera. It's a fortunate rereader who knows half a dozen novels this way in their lifetime. I know one, Pnin [by Nabokov], having read it half a dozen times. When you enter a beloved novel many times, you can come to feel that you possess it, that nobody else has ever lived there. You try not to notice the party of impatient tourists trooping through the kitchen (Pnin a minor scenic attraction en route to the canyon Lolita), or that shuffling academic army, moving in perfect phalanx, as they stalk a squirrel around the backyard (or a series of squirrels, depending on their methodology). Even the architect's claim on his creation seems secondary to your wonderful way of living in it.