If you have time to be in Mpls - consider takeing the transit train downtown and visiting the old grain milling district - http://www.minneapolisparks.org/default.asp?PageID=4&parkid=413

May as well do the Mall of America - transit train goes there also. The train is safe and easy to use, and all from the airport. Rental car is easy to get around with also, to those areas. Eastern Mn (bluff county) is kind of neat to travel through, Hwy 52.