I've never been a fan of the huge bookstores, but Barnes and Noble is better than most. The staff typically know how to find what your looking for, although it can be difficult finding someone to help you.
The selection of books is good, and they will order just about anything for you. The organization can be odd sometimes, and the alphabetization withing a letter (Ab vs At) is not always done correctly.
The best part of this store, for me, is their hardback reprints of classics. These little books are the perfect size (the print is very small, however) and come with their own ribbon bookmark.