I think you have DC and SF backwards. I haven't spent a whole lot of time in DC, but my understanding is that the word "sexy" doesn't really come within ten miles of the place. Here in SF, I think the main thing the women are aspiring to be is tall.
DC has often seemed to me like a place where people desperately want to be sexy but mostly can't make it work because they smoke too many cigarettes and spend too much time angry about all they've sacrificed for the relatively little they're ever likely to acheive. Isaac may be right about the aspiration, and Spacewoman nonetheless correct that DC is generally unsexy.San Francisco is more complicated, but there is certainly a milieu (or rather there are a number of them) for which Isaac's observation would be fitting. Others place a enormous premium on being sexy after some pattern or other (jet set, fitness freak, leather man... the list is endless).As for Los Angeles, I'm pretty sure that's dead on. I rarely go to Los Angeles, but readily believe anything and everything I read about it on the internet or watch concerning it on television. No reason to make an exception in this case.
As my husband likes to say, San Francisco is the city that never wakes up. So much sexy bedhead in SF.