If you are looking for a place to go that is close to the Twin cities consider visiting Taylors Falls. We went there a couple of weeks ago and enjoyed walking through pothole park (Interstate Park) and we on the paddle boat ride on the St. Croix River.
Taylors Falls is especially beautiful in the fall and is one of my favorite place to go and take pictures of fall colors . . . not that we need to think about fall in the middle of summer.
Minnesota is a beautiful state.