I went to San Diego for the first time this past summer for a friend's wedding. SD is beautiful and a very outdoorsy town. We stayed at the Bahia Resort Hotel in Mission Bay where the wedding and reception were held ---
http://www.bahiahotel.com/index_flash.html
I found this website to be very helpful:
http://www.entersandiego.com/
We were there mostly for the wedding but we also drove around alot, went to a mall downtown, to the beach, to the San Diego Zoo, and nearly drove down to Mexico but ended up not having enough time.
For shopping we spent a lot of time in the Gaslamp Quarter -
http://www.entersandiego.com/Gaslamp.cfm
And we had great food in Old Town -
http://www.entersandiego.com/old_town.cfm