I carried out about 90 hours flying in just over 5 weeks Aug-Sept 07, based out of Gillespie (KSEE) near San Diego.
Weather was predictably sunny and hot and there was tonnes of places to see. I landed up flying up and down the coastline many times, making excursions to the Grand Canyon, Vegas, LA basin many times (night flying is brilliant - ATC might even let you carry out touch and go's at LAX if it's late enough)... even made it to San Fransisco and back in a day with an instructor friend!
Just make sure you don't fly alone over long distances, plan your routes carefully and make sure your aircraft rental is from a solid/reputable hire company.
Palm Springs was a blast, I flew in and out of there a few times too. Watch the density altitude on hot days - it can catch you out!
Big Bear is a really cool place to fly into as well - it's one of the highest places around, elevation of 6752":
PilotAge - Airports of Southern California
Fun Place to Fly - Big Bear Airport, Big Bear, CA
Oh... and watch out for windshear at some of the airfields/airports within the Mojave desert - again, be sure, be safe!
Make sure your camera is fully charged - you're bound to have incredible times/memories I'm sure!
