There are some nice wrecks on the eastern side of Lake Michigan. Here is a charter that I used. Their web site isn't up to date, so I don't know if they are still running.
Obsession Charters, L.L.C. - 1-616-847-2908 - West Michigan Shipwreck Diving
Gordon quit running charters last year. Tim Marr still runs them Advance Scuba & Paintball
Most of the nice wrecks are deep over here but are some of the best in Lake Michigan. The Hennepin is the Great Lakes first self unloader in 230' of water. Then there is the SS Michigan and Akeley in 270' of water which are both awesome wrecks.
JT