Jim Stewart wrote: (clip) If the wife and kids aren't interested, drop them
off at Sutter's Fort while you go see it.
^^^^^^^^^^^
You will want to see Sutter's Fort yourself, but that's not a problem. If
they REALLY are bored with the railroad museum, it is located right on the
edge of Old Town, which is filled with charming little shops, antique
stores, and places to eat.

This is off topic from your request, but there is a group which meets in
Oakland (across the bay from SF) called
Bay Area Engine Modelers. They build and operate small engines--mostly
internal combustion, but also include some others. I don't remember whether
they deal with steam, but I remember one that ran by being placed on top of
a cup of coffee, and ran the opposite way when placed on a bowl of ice.

There used to be a group that had some tracks on the edge of Tilden Park, in
Berkeley, but I don't know whether they still exist.