Sep/Oct 2 night couple trip in MN--suggestions?

Just got back from the bluegrass festival near St. Cloud, MN, and I suggested to my wife we take a couple nights and three days hiking within 4-ish hours or less from St. Paul. I thought I'd take the question to you experts here--what's a killer (killer beautiful, not killer gruelling) hike for a couple to get away? Perhaps a loop that has us out two nights and gets us back, or a through-hike that we can take a bus back or something.
Any ideas?
Jonathan in St. Paul