Done it a couple of times and a lot depends on how many hours you want to do in a day and the size of the boat. Be ready to motor uphill most of the way though.
If you can get an early start, you can do SD to Dana Point. Dana Point has guest slips that you can reserve, or use the free anchorage. From there, Newport Beach. Guest moorings are $5 a night, but bring two very long lines. Mooring balls are fore and aft. The last leg is a long slog home past LA/Long Beach Harbor and around Palos Verdes. The winds can howl in front of LA Harbor and will be on the nose, so leave early.
Last time, I did SD to Two Harbors/Catalina. It was about a 20 hour trip, motoring on a slow heavy boat. But it was a lot of fun depending on the crew. Then it is just a couple of hours over to Redondo Beach from there.