When I lived in MI, I'd go on line and see who had the best deal. I'd get the phone number so I could call the shuttle if it didn't come for a while. Early on, I had great luck at the Big Blue Garage, but then they outsourced the shuttle and it was really bad.

I lived far enough away that often I'd stay at one of the hotels that had a parking deal with one of the lots. I could generally stay free for the amount I saved on parking.