If you have a few hours to kill and could use a cup of coffee or pastry, you may want to head to German Village. First of all, GV is a lovely place to wander around. Secondly, you'll find the Book Loft right by Cup O' Joe.
This labyrinth like, old house of a structure has ONE bathroom and 32 rooms full of books. Take the map offered upon entrance, but resist the urge to look at it until you've twisted back in a few rooms. It's all divided and organized into your typical bookstore sections, with a few atypical ones thrown in. They have quite a large kids book section if you can find someone to read you a good story while you finish off your coffee or tea and relax in a nook on the floor somewhere. You can generally find your selection at a discount, too.
Be careful where you park, though, or you'll end up using your discount to pay part of a parking ticket.