As a writer and avid reader, I have too many books to keep up with them all, and once I've read them, I have to pass them on to make room for more. I love Books Plus because it's close to where I work, so I can swing by on my lunch hour with a bag of books and trade them in for store credit.
They rarely (if ever, it's never happened to me) pay for the books you offer them, but they will give you a fair deal in credits and I'm always up for a free book or three. Also, they will take just about any book you bring in to trade, as long as they don't have a copy already in the store (there are exceptions to this ~ no ex-library books, no book club books, nothing pornographic in nature).
The bookstore is crowded, the close shelves towering over with books, but that just adds to the ambiance. I love it here! I could spend hours (and I have) browsing their selection. The owners are very nice and don't rush you out, either. A good experience all around.