There are all kinds of things to do around San Diego. If you're downtown, take the ferry over to Coronado and ride bikes around the area. You'll get great views of the bay, ocean, and bridge, and be sure to stop by the famous Hotel Del. Every visitor should spend some time walking through Balboa Park while. At night you'll probably want to check out the gaslamp district downtown and if you want to see amazing views of the city and water, go for a drink at the top of the Hyatt. Show up early for sunset because the good tables go fast. Mission Trails Regional park has some good hiking; Cowles Mountain is a popular trip. You could also head out to Lake Murray, rent a canoe and have a picnic.

Further north in La Jolla, get to the coast and watch the fliers do their thing at the Torrey Pines Gliderport. The Torrey Pines trails are nice also, and as long as you're in the area, take a walk down to the La Jolla Cove and south to Children's Pool where the seals hang out. Definitely one of the best pieces of coastline in the area. There are also some sea caves that can be explored by kayak.