There is a lot of poop on the island, literally.
It is one of the largest tourist attractions in the Midwest.
Lots of t shirt shops and a lot of fudge.
The island is beautiful, but there are a lot of people there.
We stayed at Mac City Marina and used the ferry service to get to the island.
Our next time up we plan on staying at St Ignace, but I do want to spend a night or two on the island just to say we did it.
Since you cruise to Charlevoix, than I am sure you are familiar with Gray's Reef just North of there. Be careful going through there.
The Mac race is in mid July so avoid the island around the 20th (I think). Not sure when the Bayview Mac would be arriving.
The docks are now State run through the DNR so you can make reservations through them.
DNR - Mackinac Island State Harbor
I am sure you will have a great trip, have fun and enjoy.