I forgot to mention: I attended the MIT Flea Market last weekend, but I didn't buy anything oscilloscope related. (I almost bought a Tektronix 7904 with a bad focus problem, but somebody else beat me to it. That's OK; I didn't really need another 7904 project.) I did, however, happen to wander through the Stata Center, which stands on the former site of MIT Building 20. On one wall in the lobby, there is a display of photographs of famous people from Building 20, including this one of Norbert Wiener with a Tektronix 541 scope in the background.
I also took my kids to a small community museum last weekend, where they had a large model train layout (my son lost his mind). In one corner of the museum they had the following sign.
Of course, I left a post-it note that said "vintage Tektronix oscilloscopes". Unfortunately, the display case for these "member collections" was only the size of a small bookcase (about 30 inches square and 8 inches deep), and it was currently filled with porcelain cat figurines... but I did ponder for a minute, "Wouldn't it be cool to put on a temporary museum display of my scope collection?" I wonder if there are any local museums that would be interested in that?