Rawhyde Off-road Motorcycle School: (for 650cc bike and larger), in S. Cal. 2.5 days of instruction and great food. Over-all, I think the class was very beneficial and was conducted in a professional manner in a truly unique training facility, quite conducive to the training goals.
MSF Dirt Bike School: Good review -- but geared more for for total nOObs.
I rode in on a horse and can't seem to get out of LA.