the smartest thing to do would be to drive straight to L.A., drive around for three hours (that should just about get you from the south to the north end) then promptly turn around and drive back to S.D.
after the L.A. experience, you'll love absolutely everything about it.
go see whatever band is playing at the casbah. eat at hamburger mary's in Hillcrest, a really hip, fun (and sometimes gay) burger and beer joint with curbside parking. get dressed up and have cocktails at Mr. Bertrand's "A" Lounge and restaurant (ask any local where it is; he'll tell you.) go barhopping and nightclubbing in the gaslamp district. san diego is a great city.
If ya got a baby sitter....The turf ckub for dinner, you can cook up your own steak on the grill. Another great dinner joint is the south park grill. bars=Whistle stop, casbah, ken club. Gaslamp is for frat boys and meatheads.
thanks halwade... you're mcgoo right? damn i miss my bmx days!
lots-o-good stuff mentioned already. a couple that haven't been mentioned are the san diego zoo if ya got a full day for it (i know; everyone knows about the zoo, but it hadn't been mentioned); and the USS Midway is a permanent museum now. the old lighthouse is pretty cool. for those of us who only see an ocean every several years or so walking/playing on the beach is a treat.
there's a really good mexican restaurant down in the original part of SD (old town), but i can't remember the name. i could drive you to it, though. if you get to Taylor St & Calhoun St you might not be there but you'll be reaaaalllllly close. maybe some of the natives on here can remember the name of the place.
'course there's prolly hunnerts of good mexican restaurants in SD.