I like Michigan a little more too. It is roughly 560 for me going most direct route. But that won't happen. OK was roughly 775 and doesn't include any driving to different points.
On to the showers now, are they wheelchair accessible? If not the only thing I'd be able to get by with would be a spot to refill my water tank and the freedom to dump shower water to the ground if I have to. Myself I can use the showers but my friend that would be coming with has a much harder time.
Advantage with MI is I could take the bus on a boat ride http://www.ssbadger.com
which I want to do anyways and then I can take the scenic route north to the mackinaw bridge and cut over towards Duluth to go home.
To me the thing that makes sense be a more of a regional thing instead of a centrally located event. Fuel cost kill us all let alone the time it takes to get to a place.
I just looked at it and by taking the boat across it is 515 miles one way to Sturgis MI. Of coarse it would be more than $245 for two of us to ride across with a bus.