Virtually the entire way up the coast after LA is wine country. Santa Barbara has several nice ones with tasting rooms in downton making tasting a several places close and compact.
A bit further up the coast is Lompoc/Santa Maria with dozens of wineries and an up and coming wine scene.
Then basically all the way up the 101 to the South Bay are even more.
Then you get just east and north of SFO and you hit Sonoma and Napa.
Honestly, the tasting experience in Sonoma is better than in Napa. Napa is overcrowded, expensive, and expensive. Crazy expensive. Good though, just not a good value.
A little further up the 101 is northern Sonoma and Dry Creek Valley which is a personal favorite. If you want details send me a PM of some great places to visit. Some highlights: Ridge, Armida, Truit Hurst (just a head's up a fantastic place for a picnic down by the river), Fritz, Dutcher Crossing, Mazzocco(Crazy dark and robust Zinfandel) And dozens more.
And if you have an extra day, Amador wine country is fun and a fantastic bargain compared to Sonoma/Napa. Particularly good for Zinfandel and Italian varietals like Barbera. Again, pm if you want details. Amador is now, what Sonoma was when I moved here 30 years ago. Not corporate, unhurried, underrated and thus a little less expensive, though that's changing fast. It's also fairly compact and easy to get around.
Enjoy your trip to Northern California. Hopefully the rain stops by the time you get here. This has been the wettest and coldest winter here in YEARS.