Barnes & Noble vs The Library

I was thinking about this the other day on my way home from work.  If I had an hour to kill, I’d much rather pop over to my local Barnes & Noble (B&N) rather than the Arlington Public Library or any library for that matter.  My first thought is to buy a book from B&N and not to go to my local library.  Why is that?  What does B&N offer that libraries don’t seem to?