I agree with saucemaster about the word "suburb". It isn't a great descriptor. If you take the example that iammatt uses, the bay area, would you consider san jose a suburb of san francisco? its 60 miles away and has a population larger than san francisco. I would disagree that there is no cultural stimulation. there are huge ethnic communities here as there are HUGE Vietnamese, Indian and Latino populations there. Maybe lacking in art, but not culture. is it a suburb because much of it is master planned? because population is not as dense as SF?
Is Oakland a suburb of SF? it's closer to SF than San Jose, but it is older and not master planned. It also has strong ethnic communities, but many tend to be middle and lower middle class.
I think what this all boils down to is that people tend to be with like minded people. and people in similar situations, with like minds, tend to find similar solutions.
The population in the urban area's of cities tend to more creative and are driven buy the satisficaton of thier soul. They are willing to do this at the sacrifice of other parts of their life.
The people in suburban areas are striving for more..... they want to live like the more elite class, but be able to do it on their current budget. More house, more safety, more cars... just more. In order to do this they may have to move into suburban areas. I can, for example, move 20 minutes from my current residence and double the square footage of my house. I would be moving into the suburbs, but I will be getting more for less. I also couldn't buy a house in the "HOOD" in SF for this same amount of money. more for less is what has driven much of this and this is the class that is in the suburbs.
I was born and raised in san francisco, but may never be able to afford to buy a house to move back to the city. This is not an uncommon situation and in the bay area, at least, this is what is driving, much of the movement to the suburbs.
Maybe the suburbs are the H&M and forever 21 of living and the urban centers are Neiman Marcus and Bergdorf?
Sorry for the long first post.... just a very interesting subject and commentary on todays society