He won't be disappointed by the Ford Museum and Grenfield Village. Plan a full day for the museum and a full day for the Village.
Ford also just opened a new exhibit called "Spirit of Ford" at the museum complex. While it's more of an advertisement than the museum and Village, it's still very worthwhile if you're into cars.
Also, if you're coming in the summer, call ahead or look at the website for Greenfield Village. They have something special going on almost every weekend. The thing that might be best is the Pageant of Power - some time in August, I think. Steam engines, gigantic oil engines, any number of tractors an steam traction engines, &c, &c.
Enjoy the visit.