Planning a trip to Germany

[zen]

I am in the midst of planning a summer trip to Germany. It will probably be a 10 day trip or so. Looking for opinions or recommendations on where to go. Obviously considering the Porsche and VW museum, but looking for creative ideas. Only must on the agenda is visiting my Grandmother just outside of Bonn and will probably fly into Frankfurt. Also will have a 5 and 10 year old will me. Will probably end up near Muchen at some point as well.