Setting
The Computer History Museum has the Difference Engine sitting in
their front lobby where it can be dimly seen through the windows from
the street
The Museum created a nice setting for it with tastefull lighting,
informative posters, and a beautifull wooden base. The machine
will only be on display till May 2009 after which it will disappear
into a private collection. I would encourage anyone in the bay
area to go take a look in person while it's here. Visiting is
free and there is a great demonstration of how it works at 2pm everyday.