Take an day or two and go through the Black Forest: Freiburg, Rotweil, Titisee etc. Cruise the north "coast" road of the Bodensee. I could happily live on the Bodensee coast.
Whence to the Alps.
I am a huge fan of the Austrian Alps. Sadly though, some of the more scenic places/roads require a very nimble chassis - and (when I was there anyway) had fairly frangible road surfaces.
Jealous? - me? - Yup.
I should be home (Brittany Ferries willing) should you decide to add Spain to the trip.
If you are going into Switzerland - DO NOT FORGET THE MOTORWAY TAX THING.