Im moving to San Diego 9-1-12 and am looking at the Mission Valley area and also around Balboa Park is?

Mission Valley is almost all condos and apartments and is mostly young professionals. It is also a major shopping area with two major malls, movie theaters, restaurants, Ikea, Costco, etc. There is much less residential and street crime there than the areas around the park. The park area is more urban and older that Mission Valley. Virtually all of the construction in Mission Valley occurred after 1970. Most within the last 30 years. The trolley runs right down the middle of the valley so it's much better in terms of mass transit. Anything on the trolley line is a major plus. The trolley will take you right downtown, the stadium or right to San Diego State, among other places. It's the best way to go to these places.

BTW North Park and Hillcrest are considered the center of the gay community. Not that there is anything wrong with that.

You're probably better renting around the Mission Valley area. You can also rent in other parts of the city where it cost a little less. And if you are single and want to meet a straight person stay away from Hillcrest. Most of the places are pretty boring there anyway.