LA is a huge, grimy, blob. :o
Go to San Diego, which is clean and all you really need is between La Jolla and Downtown, unless you want to trek south a bit more and go to Tijuana.
La Jolla upscale shopping is nice, even if you’re just looking
Mt. Soledad gives a great view of the city
Hit Pacific Beach and have some coffee on the Boardwalk
Ride an old-fasioned roller coaster in Mission Beach
Visit Sea World
Visit the San Diego Mission in Mission Valley
Visit the old San Diego Presidio site where the city, and state, really began
Visit Old Town, the oldest European settlement in California, for a margarita and a walk through history
Visit a nice downtown business district
I don’t normally recommend malls, but take a peek at Horton plaza downtown
Go to the restaurant/observation area at the top of the downtown Hyatt for great views
See the beautiful Victorians in the historic downtown Galslamp District, a great place for night-life
Visit the world-famous San Diego Zoo & museums in Balboa Park
Head out to Point Loma to see the lighthouse and Cabrillo National Monument. Breathtaking scenery.
Drive over the Coronado Bridge to Coronado, kinda more upscale shops. Visit the historic Hotel del Coronado. It’s where the US President usually stays when in town. It’s supposedly the largest wooden structure in the US & built without blueprints.
If you are more adventuresome, take the trolley down to Tijuana. Watch your wallet. Dont’ eat the food. Don’t drink the water, including ice.
San Diego knocks the pants off LA, unless you specifically want Disneyland, scummy Venice Beach, dirty overrated Hollywood, and the boring Queen Mary. Yes, all of these things are in LA, but are about an hour apart thanks to the sprawl and congestion.
San Francisco is high density, but the place is so small, it’s ok, unlike LA.
All the things I mentioned in San Diego are all within about 15 minutes of each other, at most. You can find reasonable accommodations at Hotel Circle off of Interstate 8 in Mission Valley. It’s centrally located.