The farmer's market at the capitol.
Union Terrace. Great people watching. Maybe find a cute boy with a sailboat and go sailing on Lake Mendota.
Spring Green, WI just north of Madison. The American Players Theater is first rate. Frank Lloyd Wright's Taliesin is near by as well.
Just a little further north is Baraboo, WI and the Circus World Museum. Tons of restored antique circus wagons.
The House on the Rock is a real hoot. I can't describe it but look it up.
If you enjoy nude beaches there is a wonderful one on the Wisconsin River outside of Mazomanie, WI.
All these attractions are within roughly a half hour of Madison.
Hope this helps. (Yeah, I'm kind of in love with the area).