The hostel in Sacramento is an old mansion. Really cool architecture. The capitol building is a must see if you have political interests. Worth the trip alone. Sutter's Fort is pretty good, but definitely geared for school aged visitors. The adjacent Indian museum is small but full of artifacts. They make it pretty clear what the white man did to the natives when they arrived, and they don't pull punches. The railroad museum has about a dozen real locomotives and perhaps fifteen cars of various descriptions. My favorite engine is the one that is 1,051,800 pounds, and it is really huge and all black.
28 nine year olds! ... Am now having drinkie.