Just visited my daughters who move to SF and LA last year. I highly recommend the Huntington Botanical Garden near Pasadena. Also, the Getty Villa, but you have to reserve free tickets to Getty in advance. We also went to a good comedy club in Hollywood and multiple vegan restaurants, if that's your thing I can pull up some recommendations.
In SF, I recommend walking the Embarcadero, with a great farmers market on Saturday, a 35min audio tour of a WW2 submarine is worthwhile. The Asian Art Museum is excellent. Golden Gate Park is very good, for at least driving through to see the windmill and Buffalo, biking or walking if you have time. Lots of food options, but stay away from the Tenderloin district unless you wanna see lots of homeless. If you have time, Muir Woods about an hour north, and some of the coastal beaches about 90 minutes south, this one
Greyhound Rock County Park & Beach was great, but there are many others. Again, one of my daughters is vegan, and the best vegan food we tried was near Monterrey about 2 hours south. If you have time, the Big Sur area 3 hours south has good beach vistas and hikes.