I have been to Santa Monica beach a couple times, and Long beach once.
Long beach we went to at night and made a big fire in one of the pits, it was fun but we didn't do much swimming there.
I am sure you could find some info on what it best for what you are looking for online.
I only went to LA twice for a total of a few days.
It is pretty country but I am not much of a water guy anyway. I think it has something to do with nearly dying a few times in water when I was younger.
