I'm going to be on Shelter Island, and I will have access to a vehicle.
Some of my favorite places near you are:
Fathom - You will be so close, I highly recommend going here and relaxing for lunch and a beer right on the pier.
Liberty Station (lots of restaurants and bars and shops); Bottle Craft (bottle shop and bar), Stone Liberty Station, Soda & Swine (good mixed drinks), & Slater's 50/50 to name a few.
Pizza Port Ocean Beach - my favorite place
Newport Pizza - awesome old school craft beer joint. Lots of fun and headaches when closing this place down.
Modern Times - Probably San Diego's hottest brewery right now. They seem to be doing everything right. Amazing beer...and higher prices to go with it.
Bay City - Really close to Modern Times, solid beers, not as hyped, definitely worth stopping in if going to MT
Food:
Point Loma Seafood or Mitch's - both have great fish and are located right next to each other. The line and wait at PLSF can take a while, Mitch's is more relaxed.
Ortiz's - Best California Burrito in town
Liberty Public Market - within Liberty Station, lots of food options, you can grab food and eat at Bottle Craft, even in the outside area.
Rocky's - This is a little further north, but I love this place. Simple menu (Burgers and fries), old school bar (21 & up, cash only)