Ah, southern California.
The San Fernando Valley long has hosted porn film producers and their multi-billion dollar industry. I can't make any recommendations myself, but some mudcatters may know of tours to their studios.

No interest?
The del Coronado Hotel in San Diego is well worth a visit. If you don't stay there, have a leisurely lunch, and enjoy this late Victorian landmark.
The San Diego Zoo and Wild Animal Park are famous and justly so. At the later, take one of the small tours (reserve).

To see the countryside ride the trolley from San Diego to the Border. About an hour's cheap ride.

Walk across into Tijuana. Take a cab to Avenida Revolucion, a prime tourist trap and indulge yourself buying junk you don't need. Or take a bus from the American side. Go to the Zona Rio and the Guadalajara Grill for fajitas and margaritas. Ask for directions to the outdoor market, Mercado Hidalgo. There are upscale shopping malls, but no cheaper than on the American side. You can buy Cuban cigars and smuggle them back.

Danger? Not as much as the news would lead you to believe. Use cabs even for short distances unless you know the city.
Don't take your car across unless you have extra insurance. There are parking lots on the American side.

I eat Medjool (Halawy) dates most days (addicted), so I was impressed by the groves- a very tall, attractive palm. At Mecca and Bard, in southern California. On second thought, nothing else to see there and it is very hot so just buy them at a grocery store. The dates are very sweet, soft, and large, they do not stick together unless compressed or it is very hot.

Joshua Tree National Park (far east of San Diego) is interesting in the spring, but summer temperatures reach 100 F most days, definitely not a time to visit.