Route advise from Wisconsin Dells to Indiana Dunes SP

You could take US39 down to I80 east, but beware the roads will have very heavy traffic in the Chicago area. Even the toll roads will be busy, but better. Have no idea the tolls as we never travel toll roads. We are not in a hurry, so work our way east on free roads south of I-80, then head north when we are far enough east for our destination in MI.