Lived in California most of my life - never been to Catalina. It's a basic little seaport village --- fudge shops and souvenirs. Weather was lovely and we enjoyed a nice lunch at a beach-side restaurant. Tender port.
Surprisingly pretty and clean port. This was a docking port which is nice and easier to get on and off the ship. Had to take a shuttle van ($3.00 USD per person) to the "down town". The beach is not a swimming beach - not very clean water but the beach and the boardwalk was pretty. You would have to go out of town to get to the snorkeling, swimming beaches.
Put on your sunglasses and keep walking -- you will get someone in your face every few feet trying to sell you all kinds of stuff!
Overnight in Cabo -- which was fun. It was so hot that we didn't spend more than a few hours in town during the day but the option was there to go into Cabo for some night life. Monday night NFL football is big in Mexico -- every bar and restaurant was showing the game and beer is cheap! Shopping is fun especially if you are interested in watches and fine jewelry -- be sure and check with the shopping host/hostess for VIP cards and take advantage of the on board seminars to find out where the deals are.
Cabo is a tender port. You can walk to the main tourist shopping area or take a cab. A lot of passengers booked their own excursions when they arrived in Cabo rather than use the Princess ones (which were rather pricey)
San Diego is a wonderful place. We skipped the Princess excursions and booked a harbor cruise on our own -- much less expensive and available right next to the cruise ship docks. Great tour of the harbor with interesting narration about the Naval ships and operations. We had been to Sea World and the Zoo in the past but those would have been great choices. Quick 10 minute walk to an outdoor "mall" --- Seaport Village for some shopping and a variety of restaurants.
Since San Diego was the first US port of entry after Mexico everyone has to get off the ship and clear immigration -- no big deal - easy off and easy on in San Diego.