In Cotati there is NorthBay Aquatics.
In Santa Rosa there is Caesars.
Up in that area, those are the best stores that you can check out. The prices are higher than you would find if you drive all the way down to the Bay Area; however, both shops seem to maintain their critters in pretty good conditions (at least they did the last time I visited them).
What sort of critters are you looking for? If you are into corals, the BAR Swap on Feb 10th is a must do.
Best of luck,
Roy