Here are some things that I find particularly amazing:
2nd floor: Periodicals. This section has moving shelves. Yes, that's right, the shelves move. It's wicked cool. It also makes me feel like I'm in Harry Potter.
4th floor: Juvenile Fiction. It has that amazing mural featured above that's based on this piece. Going there and reading kids' books is simply the best.
1st floor: Special Collections. So many first editions. You have to leave your belongings in a locker, be escorted into a room, get locked in, handed the item through a window, and then get escorted back out. Oh, and you also have to have a legitimate excuse to look at the stuff from the vault.
6th floor: I'm not quite sure what's up there. The stairs end on a landing with a row of locked doors. It's my goal to go into those doors before I graduate.
With it being 2 1/2 football fields long, holding over 6 million items, and having over 98 miles of shelving, seriously, what's not to love about this place?