We live in San Diego. You are staying downtown--do you have a car rental?? San Diego doesn't have the best transit system.
As far as restaurants go~~if you head towards Petco Park (baseball stadium) or Seaport Village, you will find alot of good restaurants.
I can't really advise on specifics, but there are alot of good ones.
Hotel Del is across the big bridge on the island of Coronado and you need a car to get there. I think there may be ferry__not sure.
All the beaches are within close driving distance. Coronado beaches are very nice, but sometimes it's not easy to find parking.
Attractions are: Seaworld, Zoo, and about 45 min's away is Wild Animal Park. Near the zoo is Balboa Park. There are nice museums there.
Also, if you look on the website for your cruiseline, then look under "ports", you will see all the ports listed. Click on San Diego, and you will see some of the attractions here.
Weather is warm here now.
Hope this helps.