SoCalCarCulture - Car Show and Events Calendar
Pick one. I have not been to any of them, but like to go to the Mercedes one in La Canada. Other then that, I am not into American iron or old cars from the 40s. Now, trucks, that's another story.
There's a local Porsche group that meet up once a month and they sometimes take a driver up into Angeles Crest Hwy for some fresh air. Great bunch. Lots of old and some new 911s. I go once or twice a year. Will post date and location for you once I get more into from them.
Worth going to Peterson's place