What’s cool about San Diego? Other than the fact that I live here? Heh, just kidding.
Housing costs ARE NOT COOL. This is an extremely expensive area to live in. Last year my 1BR apartment near Clairemont Mesa (which is kind of in the geographic middle of things) ran me $785/month. I am now in a 1BR condo a few miles away that I purchased for $256K. So it’s a tough place to afford housing-wise. And incomes, while maybe higher than some other cities, don’t really increase to keep up. SD is one of the least “affordable” places to live - in other words, it’s not the most expensive market, but the amount of people here who can afford the median homeprice is lower than most.
Anyway, having said that, I absolutely love it here. I grew up in LA, so I’m used to the Southern California weather - I don’t need 4 distinct seasons, so it’s probably most of what I love about the place. YMMV. It’s less congested than LA (though each year I think the difference lessens).
It’s not as culturally unique as LA, but it’s still got some good stuff. It’s a big enough city that you’ll get some good concerts coming through, though sometimes a drive to Irvine or LA is in order for some stuff. There are some art museums, plenty of theaters (some of the smaller ones I’ve started to discover in the past year or so), some pretty decent restaurants.
If you like outdoor activities like biking, hiking, swimming, sailing, etc. you’ll find plenty of opportunity for that. Mission Bay Park is a huge conglomeration of beaches, grassy areas, bike paths and such that are good for weekend picnics and things like that. Torrey Pines preserve has some good hiking right on the ocean, and it’s a great view of the water. Farther inland there are some nature preserves and hiking areas that are good for hiking, running, biking, etc.
SeaWorld and Legoland are of course the big attractions, and quite honestly, I don’t bother with them. The zoo (and the rest of Balboa Park) is a fun place to walk through. Lots of the museums in town are in Balboa Park, and it’s also a good place for a picnic.
Nightlife: you’d probably want to spend time in either Pacific Beach or downtown in the Gaslamp District. Both areas have high quantities of restaurants/bars/nightclubs. Gaslamp is a little hipper and fancier, whereas PB generally caters to the younger, college crowd. I’m not as familiar with the Gaslamp area, but I’ve done my time in PB bars. 
UCSD is very highly regarded, as I’m sure you’re probably aware. It’s definitely a well-respected local institution, and would be a great addition to your resume, for sure.
There are lots of great cities out there with a lot to offer, but I just love it here, and would be hard pressed to move anywhere else. I don’t hold it out to be the greatest city on earth, but it works for me, and I find I’m able to find the entertainment I want and the job opportunities I need. I’ve lived here since I came down from LA for college in 1991, but I really consider it my home.
If you have specific questions (neighborhoods to live in, etc.) feel free to ask me. If you want to talk via email, that’s fine, too.