The route that is outlined on the link is the route that Cycle America uses for their cross country ride. I staffed for Cycle America a few summers back and both rode and routed that section. It is a pretty good route - much of the route is set up to avoid major traffic. It is a little tough to do on some roads. Unfortunately, there are either wide shoulders or not a huge amount of traffic.
The trafiic is highest as you get closer to the eastern side of Wisconsin. The traffic after the ferry across lake Michigan is pretty heavy as well. The scenery across South Dakota is flat with strong cross winds. Minnesota and Wisconsin are quite nice - lots of bugs though. The section from Northfield (MN) to Red Wing (MN) is a fun section because there a 20 mile section of paved railroad bed - most of it shaded and no more than 3% grade. The ride along the Mississippi River after Red Wing is some of the prettiest you will find.
Good Luck and enjoy.