You are pretty much limited to what Dave mentioned as far as I know, if you go further North, there is Air Shasta in Redding
http://www.airshasta.com/ They have R22's and R44's, but Redding sucks in my opinion. One of the hottest places in California in the sumer and pretty wet in the winter. There is also a Silver State Helicopters in Sacramento, but I wouldn't go there if I were you.