Green Apple Books is the best, most personable bookstore in San Francisco. They have an endless arrangement of books (and not to mention some other items like magazines, movies, and CDs). If you don't want to spend the entire day there, I suggest that you walk in and ask them where to find the specific title that you're looking for. That way, it will save you loads of time; trust me. Green Apple is pretty well known to the locals, and I also think I read that Robin Williams is a fan (cool, huh?).