With the holidays coming up San Diego sees a lot of tourists. If you have family visiting like I will very soon, you'll have to plan an itinerary of some kind. Obviously, you'll be taking your relatives or friends to Balboa Park, and probably La Jolla's coast to see the sea lions. If you need to add more things, I think the Coronado Ferry can be a good addition. Ferry passengers get to see the bay and the bridge, and experience Coronado.
The Coronado Ferry is $4.25 per one-way adult ticket (much cheaper than a Harbor Excursion) and kids under 3 are free. Ferries leave the Broadway Pier and the Convention Center beginning at 9 a.m. and ending at 10 p.m. For the full schedule, click here.