Didn't read through all of the replies, but it sounds like you just want to be in Southern California. I just got back from 3 months there so I am by no means an expert, but:
I would honestly move to Long Beach. It's BY FAR the most bang for your buck rent wise, and has the best skate scene IMO. You could survive there without a car, and it also has a university. It's unpretentious, and has so many cool districts. Lots of great beach towns nearby, and obviously LA is pretty close for your big city needs. Long Beach is the perfect size city. The Cherry Park scene is amazing, and there's a couple other great parks too. Overall I was pretty disappointed in the skateparks in SoCal. I'm not a big park guy but when you don't have friends to skate with they are pretty crucial. Cherry was the only place I looked forward to going to, but I'm sure there's a lot of people who think it's boring. Stoner was obviously really nice but nothing we didn't have in Denver, and it felt sort of sterile to me, hard to explain.
I spent a lot of time in Culver City. I was trying to break into the film industry as an editor and didn't have much luck. I really liked LA, but don't really see why people who aren't heavily involved with fashion, art, music, film would want to live in LA proper. Santa Monica is very expensive and probably not the scene you're looking for, unless your a yuppie who is doing well professionally and wants to keep up appearances. Santa Monica also seemed like the worst pocket to be in traffic wise, getting out of there is awful. However, almost every job/office I encountered while working/interviewing was in West LA. West LA definitely seems like the pulse of the city, as far as business goes. If you want to stay on the west side and not pay a fortune I would check out Mar Vista and Culver City. Avoid Venice like the plague. I really enjoyed Echo Park too if you are looking for something more central. You absolutely need a car unless you happen to find a place near school/work, but you aren't going to have much of a social life or get to explore the 2nd biggest city in America. A motorcycle would be a better option IMO.
Everything you hear about the traffic is true, but I found that to be really the only drawback, other than cost (but I was coming from a similarly priced city). I want to move back and am definitely planning on moving to Long Beach this time.