It's true, you probably won't make a college decision based on library resources... That being said, our library system is fantastic!
I know of students who have never entered a library during their four years. That's an accomplishment - you definitely have to go out of your way to avoid them. We have sixteen libraries spread all over grounds. Most of them are associated with various departments, so for example- the Music, Physics, Classics, and Biology buildings all have their respective libraries.
We have over 5.1 million books. What does that mean practically speaking? You can wait pretty much until the last minute to do all your research, and chances are, our library will have everything you need. =) Not recommended!!
My favorite library is Alderman, home to most liberal arts books. It's a five floor building- though "stacks" (where the books are stored & grad students have their carrels) divides into 1/2 floors- with a lively cafe, our McGregor Room (my ten year old sister calls it the "Harry Potter room"), the Scholar's Lab (with a beautiful view of Memorial gymnasium & Nameless Field), and a ton of nooks and crannies perfect for papers & studying.