I’d suggest taking the German Alpine Road which runs from Lindau on Lake Constance/Bodensee to Konigsee. Make a slight detour and visit Breitachklamm. If fairytale castles along the route are your thing you’ll find details online. At the eastern end visit Wimbachklamm and take a trip on the Konigsee. At Berchtesgaden visit the Eagle’s Nest. Then head south into Austria and over the Nockalm Pass towards Villach where you can drive the Villach Alpine Road. (which is a dead end). Return to the main road and head for the southern end of the Grossglockner mountain road. At the northern end of the Grossglockner head east over the Gerlos Pass where you can visit the Krimml waterfalls. Continue to head east over the Silvrettastrasse Pass and back to Lake Constance/Bodensee.
There's a .gpx file of the German Alpine Road
here which can be imported into either Garmin Basecamp or mydrive.tomtom.com to view the route.
A .gpx file of the route I took with Bobar in 2015 can be downloaded
here and viewed in Basecamp or imported into mydrive.tomtom.com.
There's a video of the trip
here. If you haven't got a Dropbox you'll have to download it to view it.
