For the most part, I think a store's stock depends on the management's taste. Usually B&N and other mega stores have a good selection (like 1 half of 1 side of an isle in the Sci-fi fantasy section) but rarely more than that. In smaller sellers on the other hand I've seen several walls covered with TSR publications.
I'm in luck then, my B&N has a full double sided section with half of the second side being devoted to all the setting books.
"Evil prevails when good men fail to act." The original and unapologetic Arilyn, Aribeth, Seoni Fanboy.