Northern Lake Michigan can be a challenge for chartering dependent on your location. Sailboats Inc offers a couple of boats out of Manitowac, Wi, but very few. The majority of their business is Lake Superior and the Apostles. The Apostles are also a great destination.
Beyond that, I think that your only option in North Lake Michigan is Bay Breeze in Grand Traverse Bay.There is also a charter company out of the North Channel (Lake Huron)in Canada.
I have a boat in Bay Breeze's fleet, www.bbyc.com
, and think that the location can be a benefit, even though it would be an additional 6 hour drive. Dependent on your abilities and desire, you can have the protection of the Bay with lots of destinations within it (Traverse City, Suttons Bay, Omena, Elk Rapids, Northport, Bowers Harbor), or dependent on your number of days can venture to many places on the West Michigan coast from Frankfort, Leland, Charlevoix, Petoskey, Harbor Springs, Beaver Island, Mackinac Island, Mackinaw City, St. Ignace, etc.).
Whatever your choice, have a good time. She is a beautiful lake with lots to offer.