As San Francisco's largest and most relaxed beach, Ocean Beach is a delightful break from urbanity. Even on the warmest days, there is plenty of room to throw down a towel (or t-shirt) and soak up some California rays and play in the surf. It's advisable to bring wind protection and a warm layer, just in case :)
At night, bonfires light up the pits - for those arriving after they're (especially on weekends) a friendly approach (and some firewood/beverages/etc to share) should help make some new friends. Again, bring warm clothing!
The Cliff House and Beach Chalet provide indoor eating with expansive ocean views - Park Chalet (on the backside of Beach Chalet) serves outdoor cocktails on warmer days :)
Website: http://www.parksconservancy.org/visit/park.asp?park=68
Wikipedia: http://en.wikipedia.org/wiki/Ocean_Beach,_San_Francisco,_California
