When you say "Los Angeles Area" that's a pretty big area. Can you narrow it down a bit? What are you planning on doing? Will you be driving somewhere to visit friends/relatives? Driving in to tour LA? Going to Disneyland or Hollywood? Or are you going to be sitting enjoying the CG you stay in?
Agree that as this is the weekend before Thanksgiving getting a site at one of the premium RV parks with hookups will be hit-and-miss. Many, if not all, of the beach-side campgrounds book up months, if not a full year in advance. You may have to call around and get on waiting lists.
One more CG I would recommend you try is
Golden Shores RV in Long Beach. We've stayed there the past two years in the weeks prior to Christmas. It is a very clean resort within walking distance of the Long Beach shoreline with it's attractions and shops. Also the Long Beach Aquarium is close by.
Good luck and enjoy your trip.