We have stayed at San Onofre State Beach a couple times. The campground is on the bluffs, and nearby Old Man's beach has some of the best beginner's surfing waves in Southern California. The day use area gets crowded quickly during the summer, so be sure to arrive early. If you don't want to camp on the bluffs, consider heading a bit inland to San Mateo Campground, which connects to the beach via a 1 1/2 mile nature trail. It's a bit of a walk if you are carrying a lot of gear, but much quieter and more spacious.