You may have seen the hot deal news today of a nationwide fare sale for $400 tickets to Spain with Delta Airlines from major and many minor airports around the USA. The aspect of this sale I have not seen mentioned in other posts is the wide availability of this sale from western states airports. The other aspect of the sale is a dozen or so airports around Spain priced from $400 to $450 round trip for travel November to May, excluding December holiday weeks.
You will be hard-pressed to find a better deal to Spain from the west coast than these fares. Unfortunately, SFO and SJC do not appear to be participating, so Oakland is your best deal from the Bay Area.
I am pressed for time so here is a quick analysis showing many different western states airports and many different cities in Spain with low fare tickets.