Staying in Mackinaw City is also an option. I mean, there’s plenty to do in either the UP around St. Ignace or down in the tip of the mitt around Mackinaw, just depends what all you want to do. Though it’s not like you’re totally locked in, either, you can always cross the bridge if there’s stuff on both sides you want to check out.
(I realize the OP’s already been and gone, just wanted to point out another option in general)