Tourist destination or not, the SFMOMA Museum Store carries terrific architecture and design books and one of the most current selections of artists' monographs in the City. It's also a great place to get a gift for that cute little niece of yours as it stocks a superb graphics-heavy range of children's books. Their merchandise turns over like lightning, so don't expect them to have that Francisco Clemente biography for long. The Museum Store's sale bookrack is legendary. With almost nothing more than a pocket full of patience and maybe the aid of the part-timing art student staff, you're sure to find some real gems.