I flew about 55hrs at long beach with Rainbowair and have nothing but good things to say about them. They are based at long beach, and have three R22 Beta's - hard working machines, but well maintained. There are a couple of other operators at Long Beach, US Helicopters being one of them. I have also heard good things about them and my current FBO in the UK uses US Helicopters for the annual LA Heli trip.
Hope this helps
CRAN
www.rainbowair.com
www.ushelicopters.com