If you're in Sac., I think Pat's suggestion is probably a good one. You'll likely do as well on the American, Feather, Russian, Eel, Mad, Matole (is that right, the one I"m thinking of?) as any river here in the PNW. If it's a change of scenery you're looking for and want to travel here, the Bogachiel on the Olympic peninsula is probably the most productive river in that time period, followed by the Hoh. But don't expect solitude. You'll be fishing with about the same number of "friends" as you would on the nor Cal streams, from what I've heard about nor Cal steelheading.
look for rivers with big hatchery runs. seems you dont see many wild fish till later in the winter. op rivers might be a different story, never been there. sounds like 99% of the WA population is piss pounding it with bobbers and beads after summer run fishing tapers off. fishing with crowds like that is not my cup of tea. how do you like to fish, and where do you usuallly fish near home ?