I am looking for ideas for our trip to Germany the first 2 weeks of June. We will fly into Frankfurt June 5th and will plan to stay 8 to 10 nights. My group includes my parents who are in their early 80's, mobility is a little limited, and my college aged daughter and boyfriend. I am probably only going to staying 2 or 3 places to make the trip easier on all. I am looking for places to base out of and activities in each of the locations.
Right now I am considering Rudesheim for 4 nights with the idea of seeing the Rhein valley and taking a cruise on the river I am then planning on heading to southern Germany to see Bavaria. Visiting Berchtesgaden and Salzburg are probably priorities on this part of the trip. Looking for 1 or 2 other places to base out of that gives us access to southern Germany. I am planning on renting a van so travel mobility will not be a problem. Recommendations renting a vehicle?