I was waiting to see if any locals replied, as I only visited LA once for kiting. From my expereience I can tell you its not exactly a kiting mecca as you can only kite half the days or less even during the peak (spring, summer) season. However, apparently you can kite in the winter there, so thats pretty nice.
El Segundo would be a good spot because its right between Seal Beach and Malibu, which seemed to me the best places to kite at the time.
One thing you might consider is that kiting might get banned from most of the good spots. I believe when I was down there it had already been banned from a couple beaches, and the others usually required you to check-in with a Lifeguard for the "OK" before rigging up.
The two places I rode while I was there were Topanga and Seal Beach. Both were frustratingly too light at the time I was down there, but they were both really nice beaches with pretty warm water (it was July and I wore just a rash guard.) The winds in the summer are pretty light, so you would probably need a 16m and 20m, as well as a 12m for the stronger winter winds.
Anyway, if you have compelling reasons to move to LA other than kiting, I'd go for it. Otherwise I would consider another spot (Texas, Gorge, Hatteras) as LA is the armpit of the world in my opinion, and it'd take more than okay kiting conditions to get me to move there.