I was just in Berlin this weekend and I thought I'd put in a plug for the Musical Instrument Museum and the exhibition they're putting on about Berlin violin makers. It's a chance to see a bunch of violins by several makers one hears about west of the Rhine, but of whom one rarely gets to see an authentic or representative example.
I very much appreciated the permanent collection as well, (surprised by the dramatic, almost Del Gesu-ish corners on an Edlinger viola) and liked the way they organised the "German language sphere" violins into seperate glass cases for Allemanische, Saxon/Markneukirchen, Tyrol/Bavarian, and Viennese schools.
P.S. Try to go when there isn't a demonstration of the Wurlitzer organ going on...