Dewey hit pretty much all of the hotspots. Itasca state park is our favorite state park and there you can use your scooters throughout the park as well as the wilderness trail. It's 17 miles one way from start to finish and it's very scenic.
More central is the Brainerd Lakes area. This is a pretty touristy area, but there are lots of little towns to visit (Nisswa, Cross Lake) and 2 COE parks that are nice.
For casino camping further east near the Wisconsin border is Hinckley casino and the campground there has been voted one of the nicest in the country.