Does what you read vary by the season? For instance, Do you read different kinds of books in the summer than the winter? Not intentionally. I try to keep what I read varied throughout the year. For the last couple of years all of my reading was determined by commitments made through BookCrossing. It's only since last summer that I've met enough of those commitments to be able to pick and chose some reading strictly for fun.
If so, do you break it down by genre, length of book, or...? The only exception to the rule is books for travel. If I'm going on vacation, I'll probably take books that are easier to read and are ones that I won't mind if I accidentally lose (or "wild release"). I once made the mistake of taking The Peppermint Pig by Nina Bawdin on vacation (Salvage, California, I think) and the book got shoved under the bed when we were packing our suitcases for the return home. Had it been my book, I would have been disappointed with myself but it was a library book! Thankfully the motel found the book and was kind enough to send me the book.