Have fun at the conference- I have some coworkers that are going to it, too!
My DH works in Madison & I've gone there a few times with him.
UW-Madison has a great student center/student union that has a bar. There is usually music on a veranda type of thing overlooking one of the lakes, and there are bars outside as well.
State Street is fantastic- lots of bars, restaurants, cafes & shops. There is a great tea house & little curiosity type of shops. I have lots of jewelry from Art Gecko (it's been DHs go to place for gifts since our dating days).
Have fun!