The Ludington Ferry used to operate from Milwaukee, WI across Lake Michigan to Ludington, MI and that is how we started our trip. I used to live in Hinsdale (suburb of Chicago). Now it operates from Manitowoc, WI to Ludington. Still a cool ride to make a part of a trip around Lake Michigan.
A bit of clarification on this. There are 2 ferries that run across Lake Michigan:
The Lake Express Hi-Speed Ferry runs from Milwaukee to Muskegon, MI
The SS Badger runs from Manitowoc, WI to Luddington, MI
As far as I know, at least as of last summer, both were in operation.
I love the scenery, but the weather can get interesting.
The thing a lot of people don't understand -- probably because we call them 'lakes' -- is that L. Superior and L. Michigan are in fact inland seas. As such, they generate their own micro-climates. It's not unusual to have beautiful weather inland, and run into rain/fog and a 20-degree temperature drop at the shore.
That being said, both of my trips around Superior and Michigan were blessed with phenomenal weather.