The water on the scenic part of SR1 is cold and the climate can be foggy or chilly. I would not view anywhere along the coast around Big Sur as a beach destination.

There is some hope further south, such as San Diego. But there are no hotels with really private beaches.

That's because California law states that all beaches from the mean high tide line out to sea are public property. People do try to limit access but anyone who gets to your location from adjacent property, a coastal access trail, or via the water is allowed to be there.