I've not ridden in Germany, but have travelled there by car on a family oddyssey.
Of all the places we saw, there were a couple that stood out to me in spades, that would be great to tour on a motorcycle.
http://en.wikipedia.org/wiki/Saxon_Switzerland is just near Dresden, so may be too far from you for a 3-4 day trip.
Down south, around Oberammergau, Linderhof and Garmish Partenkirchen (and the Schloss Neuschwanstein) is great too.
If you're looking at the Western egde, I found some neat roads just off the Rhine between Rhudesheim and Koblenz. When you're done riding, have dinner in one of the restaurants in the Drosselgasser in Rhudesheim. If you're into Falconry and walking up hills, go here
http://en.wikipedia.org/wiki/Burg_Maus
I can't recall exactly where, but there are some roads around Hannover and east that are closed to bikes on weekends.
Just a few more ideas to whet your appetite!
Mick