I'm planning to attend the Spa 6 hrs in May.. to spectate and not to drive unfortunately.

I also plan to visit Stuttgart at that time to visit friends, but of course the ulterior motive is to visit the Porsche factory museum. It would be nice to see the place I bow and pray towards every time I go into my garage to work on my car.
Anyone ever been to Spa and have suggestions of how best to enjoy the event, other things to do or visit in that part of the world?