I am very familiar with the two California beaches. Carlsbad and La Jolla.
IMO the beaches in both cities are two narrow. In high tide everyone gets pushed off the beach. The beaches to the north are wider and more space but dirtier (example KFC buckets floating in the surf and people swimming in street clothes.)
I live in Oceanside which has a long enough beach to surf, longest pier in the US, but still narrow like Carlsbad.
Tourists come here for the general weather and the beach included. If you plan to come try Carlsbad with a nice walk around village vibe downtown.
La Jolla is upscale and pricy, with a scientific educated community. Harder to park and crowd on the beach in good weather.
If you want san died o to Mission Bay area. bigger beaches more people but mor space and near the main San Diego attractions. Plenty of hotels various price ranges (unique La jolla).
Oceanside has space for surfers and swimmers at the same time.
Lived in SD (Rancho Bernardo area) before we left CA.
We traded the ocean for the Sierras.