The northern part should be the long-proposed State of Jefferson. (If Jefferson's name is now too controversial, call it Sierra.)
I would then have the area including the Bay Area, Sacramento, and maybe Santa Cruz as Northern California. Make a state of the counties from Santa Barbara to Orange County (add the parts of Riverside Co. and San Bernardino Co. which are spillovers of the LA megalopolis) and call it Los Angeles. So people can say "LA,LA," like now we have "New York, New York." Then the rest of Southern California would be the remaining state so four in all.
Conservatives would have a chance of electing senators in Jefferson/Sierra and perhaps in Southern California.
I would support a state of Jefferson in a heartbeat.