A few fellow hills-crazy cycling friends and I have been riding up and down Mt Helix in La Mesa a lot lately. It is such a beautiful place with sleepy streets and friendly locals. I don't need a lot of incentive to head that way as soon as I hop on my bike in the morning. All I need is < 87F weather forecast, and I'm there!
Even if you don't like musicals, it's still a super cool place to be. Usually you are ushered off the mountain withing 1/2 hr after sunset, but during the shows, of course, you can stay longer. Check out http://christiancommunitytheater.com/ for tickets. The show goes on at 8 pm on July 23, 24, 25, 26, 27, 30, 31, Aug 1, 2.
I'm afraid there's no parking up at the theater for this (there's a lot, but it's way too small). You'll have to park off Vivera opposite from the fire station near the base of the hill and take the shuttle bus up.