Recommended sites around the San Diego convention center [closed]

I'll be in San Diego, CA (USA) for about 3 days next week and was wondering what are some of the recommended places to see in and around the San Diego convention center if I have maybe a day's time for sight-seeing.

Yes, I can visit Tripadvisor (of which I am a regular contributor of articles) et al but somehow that seems very impersonal and the reviews are extremely mixed and by experience I find it is difficult to judge a place only by tripadvisor's remarks.

My interests lie in:

1. Sight seeing/Art
2. Eating (lacto/ova vegetarian)
3. Shopping (low budget, < $100)

I will not be renting a car. I will have perhaps a total of 12-15 hours during the entire trip for recreation.

Edit:

As per Karlson, I am not expecting anyone to be a psychic. If I knew what kind of memorabilia I'd like to pick up, I'd probably not post to travel.SE.

If you anyone has two cents about what to do in San Diego without needing to be psychic (since I am not trying to hire travel agents here), do leave a comment.