I don't think you can ever spend too much time at the beach. Even after backpacking and practically living on the beach, I still love the relaxation that comes from a day at the beach. But we have hardly gone to the beach since being in San Diego. I don't know why, but we've been irresponsible on that front. :)
But we still managed to spend at least one day a month at the beach. The last weekend in September we headed out for a few hours, just to soak up some sun on an otherwise uneventful day.
The water is really warm in September (warm for California) so we had to go into the water before the ocean turns back to ice. We walked to the shore, counted to three, and ran into the water, diving into the first wave that was above our waist. Surprisingly, it was really nice.
The next weekend, we went out to Octoberfest in La Mesa. There wasn't a ton for us to do since we didn't need any crafts, and we ate before going, but it was still fun to walk through the super full downtown streets of La Mesa. Caitlin became a work of art as the Mona Lisa.
It was fun just spending the night out walking around. It reminded me of the ferias in Mexico we used to go to. We walked from our house down there, and chatted with a guy from Senegal who made bracelets and baskets, and a woman from Guatemala that was selling artisan crafts. All the world collides right here in San Diego. We absolutely love it.