Old Sacramento (which is where the CA State RR Museum is located) runs train rides on weekends and Tuesdays, if you're in town for that time.
WP is up in Portola - quite a drive from Sacramento. Keddie Wye is about 45 mins to an hour from that.
There's also Railtown in Jamestown, CA that's pretty darn awesome. Nevada County Narrow Gauge too.
I can send you to the best train shops in the Sacramento area too, if you're going up I-80 or or 50 through town. If you're headed North up I-5 towards Oregon, there's the Skunk train. If you're going through Southern Cal, there's more RR museum options too.
- Nevada County Narrow Gauge
Hope that's useful! I love living within 20 minutes of the CA State RR Museum, and pay for the guided tour if you've never done it - so worth it!