The Detroit area SMART bus system now has routing and schedule information in Google Transit. It gives bus numbers and times for rides across the metro Detroit area, and plans the next available trips for you.
With all of this data it now looks almost possible to schedule and plan transportation from Ann Arbor to large parts of metro Detroit on public transportation. Mind you it's a little roundabout, but you have two choices:
- take Amtrak Ann Arbor - Detroit - Royal Oak - Pontiac, 3 trips/day
- take the Michigan Flyer bus to Metro Airport, switch to a SMART bus, and connect to routes from there - allow plenty of time for transfers and to find your stops.
I haven't timed the last of these, but I'm sure it's at least three hours, maybe four if you get a bad transfer time. (ouch) But it does, indeed, look possible, perhaps even interesting in an adventure travel sort of way.