Hi Helen!
I know of one in Northern California in Old Sacramento.
California State Railroad Museum
Open 7 days a week
916-552-5252 ext. 7245
http://csrmf.org
Another one listed is: Portola Railroad Museum
916-832-4532
You can operate the Locomotive it says....
I hope you find one down south...but I think the one in Sacramento is
really unequalled. You can ride Amtrak up....the station is about 1
mile away from the museum.
Lisa Holmes
Gallerie Konzeptwerk
http://home.earthlink.net/~theconceptco/fineart1.html