I know @HFCS lives in the LA area and works on toys for films
I work with big studios to get my projects approved, but I do see a ton of small post production audio/video firms all around Burbank, Glendale, south Pasadena, and Studio City. Some actually in Hollywood. I'd suspect these small firms employ as many or more people as the big studios themselves.
I guess the best advice I could give you is to not live to far from those areas if you make the move. There's a lot of video game stuff further south toward Irvine which might be similar work, but you get away from the film/music stuff.
A little of it is scattered all over. Guy I know worked for Universal music...the main corporate is in studio city but he had an office in Santa Monica and one in Woodland Hills.
