I know HAI in florida are mostly schweizers - never been there though so cant comment on their reputation. There is also group3avaition in Van Nuys (LA) but again I have never been taught by them.
I have however visited western helicopters in Rialto (calif) whilst on a photo shoot and spoke to the chief pilot and CFI. They both had an awful lot of experience each and seemed extremely knowledgeable. There outfit for training is quite small but they do alot of commercial work. Worth a phone call
Hope this helps