Didn't want to take a shore excursion but Pier 39 is right near the cruise dock and makes a fun day looking at shops and having a breadbowl of boudin bread filled with clam chowder.
Being native CA's we have over the years seen most of the attractions however, we decided to take the trolley for a 2 hr. tour. It was very nice. We went through all the highlights of the town and across the bridge to Coronado.
Due to recent violence in Mexico, not interested in going to any mexican city. Princess port in Ensenada is very nice and separate from the town (shuttle or walk to town). Little shops are right on the dock (a bit pricey and limited) but good to get off and walk around. We have previously enjoyed the wine tour in Ensenada in which we got a good tour of the city and countryside and the lovely wineries they have.
More 
