Any "must see" areas in the GreatL Lakes region?

Bring your bicycles. Ride around the Island and there is a gravel path across the street from the Mill Creek campground. No problem parking at the Ferry and they run frequently but the earlier you get there the better. Buy some fudge on the Island.
See the old video of how the bridge was made at the pizza place in Mackinaw City. Always pronounce Mackinac as if it was spelled Mackinaw.