This is a loop my wife and I did around Michigan few years ago. It, or variant, would make a nice ride.
We have also ridden the same route out of Chicago through Indiana that was mentioned above. I gave the rider mentioned in Joe from Boston's post the information on our route. He essentially used the same route. If you are interested PM me.
If you do end up in Winnipeg, you will need to figure out how to get back to Chicago. This summer on a portion of our ride across Canada, we had to ride from Winnipeg to Fargo, ND; the nearest train station that accepted checked baggage.