Living just across the river from DC, I wish there _were_ more
mechanical music viewing opportunities!  You definitely want to
visit the Smithsonian's Piano300 exhibit.  Try to go for one of the
performance tours; I believe they're at noon on Thurs., Fri., and
Saturday.  Check http://www.piano300.org/  There's a nice Standard
Action player upright and some rolls in the exhibit; also, they don't
play that particular piano.

Also check the pianos in the Museum of American History.  There's an
art model Duo-Art grand with Concertola, a pushup player, etc.  Also,
downstairs in the ice cream parlor, there is a Welte orchestrion and
an Ampico grand.  On some weekdays around lunchtime they play one or
the other.

The band organ that used to play on the Smithsonian carousel is still
"in repair" -- it's been like that for years.  Instead they play taped
music.

I'm afraid most of the cool mechanical music in this area (except of
course the Glen Echo organ) reside in private homes.

Jim Canavan
Alexandria, VA
http://members.aol.com/vapianola