By the way you should have been able to check your luggage all the way through. I've frequently done 6+ hour layovers in Detroit (to do lunch with the family, sounds familiar?) and agents can check luggage all the way through (of course they may have to call supervisors to have to confirm that this is possible, but yes it is).

And as an added bonus, sometimes your luggage gets sent on before you and there's no need to wait for it to get spewed out last on the belt.