Pick something other than Victory Cruise Lines. The Great Lakes were a great place to cruise; just pick another cruise line. Or set your expectations low and deal with it. We did Detroit to Halifax.
For example, if you don't mind waiting 45 minutes for the crew to figure out how to put the gangway down to get off the ship at your ports of call... then deal with the limited excursion time.
If you don't mind that your port of call for a whale watching excursion is canceled and you simply drive by the area... then deal with it.
Do NOT take cabin 406, 408, or 409. There is something in the inner-workings of the ship that makes relatively loud noises all night long. I sleep through anything but it was a real issue for my light sleeping wife.
The Owner's Cabins look on the diagram like something worth considering. However, don't expect your front balcony to be private as guests from all levels access it.
Make sure you have a real good map and avoid the underground.
Pretty small town. Better if you get out and see the outlying areas.