Head over to the aircraft carrier USS Midway downtown. You can tour lots of it--including aircraft on the deck and in the hangar, the berths and the superstructure. They also have the HMS Surprise from Russell Crowe's movie Master and Commander and the Star of India.
Midway Homepage
If you are into airplanes, check out the aircraft museum in Balboa park, across the street from the zoo.
Silver Strand is a nice state beach south of Coronado. You might see the Navy SEALs doing their thing just north of there.
The Gaslamp area downtown has lots of bars, bistros, and clubs.
Be careful in Mexico. U.S. State Department issued an advisory for U.S. tourists because of the killings and kidnappings going on there. Law enforcement is . . .different than here.