Traveling The Great River Road, September or October (hotels, must see, fall)

[Ghengis]

Does anyone have any suggestions for any must see sites or festivals along the Northern half of the Mississippi River in early fall? We would be traveling from Mpls/St Paul to St Louis or Memphis. We have been as far as Galena, IL in the past and loved that town. Would be interested in hearing about similar towns, historical sites, hotels and festivals south of Galena. Thanks!