San Onofre State Park
The gay section is on the stretch of beach between lifeguard tower six and the edge of Camp Pendleton Marine Corp Base, the nude beach area.
or El Matador (northern malibu)http://www.gayoutdoors.org/page.cfm?typeofsite=storydetail&id=586&storyset=yes
"The rugged beaches of northern malibu are where Angelenos go for their fix of wild coastline---all of them, it sometimes seem. But somewhere along the Pacific Coast Highway, about halfway between the twin mob scenes at Zuma and Leo Carillo, a simple brown sign indicates you're passing El Matador State Beach. Don't. Instead, park in the tiny lot, follow the narrow trail, and descend the steep staircase down the 150-foot bluff. You'll discover a paradise only the locals know about. The crowds are small and mixed men/women and gay/straight. Towering, jagged freestanding rocks dot the shorebreak and the beach, creating tide pools and private pockets of white sand. They're the perfect spots for El Matador's prime actvity: just chilling and watching the waves break, preferably with the one you love. If it's a weekday, you'll likely have the place to yourselves. But if you're not alone head 100 yards north to a deserted quarter-mile strip of sand, where beach access is limited by the sprawling estates perched overhead. Careful: High tide could leave you stranded. Then again, that might not be a bad thing."
Discovered it the last time I was in LA - incredible.