My wife and I drove the Deutsche Alpenstrasse last August. It is a wonderful drive and trip. I offer a few suggestions.

1. Allow time to step out of your car for photographs and to take in the scenery.
2. The scenery in the Bertchesgaden National park is spectacular as you drive through it. For us this was the highlight of the whole drive.
3. If you have a Nav System in your car, definitely lay out the trip on the map and follow along with the map. The Deutsche Alpenstrasse is not always well marked and it is easy to take the wrong turn with the nav.
4. With Nav use it as a series of short destinations, i.e. the next major town. Otherwise the Nav will keep directing you to the Autobahn.
5. The Eagles Nest is superb.
6. The Rossfeld-Hohenringstrasse or Rossfeld High Ring Strasse near Bertchesgaden is really cool. It winds up to the top of a mountain range.
7. Zugspitze is wonderful, especially if you hike to the top of the mountain at the cross.
8. Garmisch-Partenkirchen is a great place to stay. Alfred gave us the name of wonderful, simple restaurant to hike up to up in the mountains. You could pm him for that.
9. Salzburg and Salzkammergut in Austria make a nice extension to the Deutsche Alspenstrass.
10. Hiking in the mountains is really fun. It is even more enjoyable with Leki Trekking poles. My wife gave me a hard time for buying them, however in the mountains she thought that they were fantastic. Hiking in the mountains in Germany is a lot of fun. I especially like the fact that the Germans do not use guardrails except in extreme conditions.

The Deutsche Alpenstrasse and these sites make a fantastic trip. I am surprised that there is not more interest in this itinerary.