The Ian's on State Street is a great place to get a slice, or two. I have to admit that I haven't had the "full" Ian's experience - haven't been there around bar closing time, or ordered a whole pizza, or visited the Ian's on Frances - but I still think overall their pizza is as good as anyone else's in Madison. They get a lot of attention for the mac and cheese pizza, and rightfully so: it's phenomenal. The crust on their pizza is also better than you'll find in most places.
Ignore the few Ian's haters mixed in here and give this place a try sometime when you're wandering around State St. or the Capitol. Chances are you'll go back ...