charter operators are somewhat territorial, I have never been out on a bad charter, but I am lucky. The question is always, how many people and is there room for the group. Charter boats are approved by the state or coast guard. The state approves 6 packs, the USCG approves some of the larger operators, though most only carry 10 to 14 divers some dive boats can accomodate more.
Check out the michiganpreserve.org website and pick your preserrves and shipwrecks. I personally can highly recommend the Preserves on the eastern side of the state and the Straits. Think about the days of old shipping was to the busiest ports. so from Detroit they went along the shore to the straits and then they went to Green Bay or Chicago some to indiana, the most went west, so more wrecks along the east coast than west...just some thoughts