Sorry, but I think trying to see the entire California coast from San Fran to LA in 4 days is NOT a good suggestion.

Actually, I don't think so too. Still, my recommendation is 2 days San Francisco and 2 days Monterey/Carmel/Big Sur. It was just meant to answer OP's questions.

louistraveler5: I didn't see you response re time of year (we were posting at the same time)

You don't have enough time for >>beach, city, mountains

Meant to add -- my >>>CaliJean: Welcome to Fodors. . . .

I've lived in California all my life, most of it in San Diego and a few in Northern California.
Go to Northern California. It's beautiful and there's a lot to do.

I've been to California twice now. Once I did the LA to San Fran drive and 4 days is not enough. This past February I went to San Francisco and fell in love all over again. It is an amazingly beautiful city with a lot to do. I won't even make suggestions. Go to Stu's link and there's enough to choose from. I think southern California needs more time than 4 days. I'm looking at going myself in February now that a beach trip isn't working out. I have about 6 days to spend. I think the traffic in LA and the different areas need more time which is why my vote for 4 days goes to San Francisco.

With 4 days in excess of travel days, you can do one of the following:

LA/Hollywood area or
San Diego area or
San francisco area.

Don't try to do more or you'll spend your trip in the car. Of course, the coast is a great place to spend in your car, so: ..

SF can be 4 days in SF, or 2 days SF and 2 days either north to wine country or south to Montery/Carmel/Big Sur. My own preference would be to fly into SF, pick up a car, and head south to Monterey area on arrival day. Next day: Monterey/Carmel/etc., don't miss the aquarium. Next day drive down Big Sur, maybe a stop at Pt. Lobos, lunch at Nepenthe, add a coastal park, turn around and stay either at your hotel in Monterey area or push to SF.

Then, shed the car and have 2 days in SF, which isn't enough time but will do for a first trip.