There's lots of us to help, but as you know, this is a BIG place. Where in LA would you like to visit? if this is just a surfing trip and you want to avoid LA traffic, you can leave Cochella, head West on the 10, up the 15, to the 138, and fish your way onto the 14 and into Santa Clarita. Here you have Magic Mountain with Travel Village next door, and the beach is a straight shot out the 126 about 40 miles or so. Or head out the 126, take a chance on several of the first come beach CG's, most with surfing right out the door. If you need reservations, call Ventura Beach Resort. Pricy, noisy, but it's close to the beach.
There are others to chime in on points further south, but the north county area, especially Travel Village is an excellent launch point up the 5 and into San Joaquin Valley
Jeff - WA6EQU
'06 Itasca Meridian 34H, CAT C7/350