San Francisco is a pretty awesome city... I think it might be my favorite. I wasn't there for very long but every single minute was full of kind of WTF weirdness that I will never forget. I've been to a few places including some in the 3rd world, but that was the most eye-openingly wild mix of pretty much everything I have ever seen.
I think most of the issues I have with Seoul and all of Korea is an overall lack of cool. Everything is suppressed, conservative, traditional, or some kind of hollow clone that misses the entire point. I guess you can have 'fun' in Seoul, but you can't do it in a unique or interesting way. Cheesy boy bands and American imports don't make you cool, you have to put your own spin on things. Tokyo does it with gusto and to such cartoonish extents its almost like satire... seriously, the amount of clever-yet-meaningless utterly disposable novelty that they cram into that city is incredible. But Seoul does Western culture like they're afraid of seeing something that they might like, or they just miss the point by such a wide margin you just wonder why they even bothered. Or sometimes they get the image right but it's just hollow and there's nothing beyond it-- images are only really appealing if there's some sort of charge or meaning behind them, the point isn't always just to 'look good'.
I don't think there are any places in Seoul that really strike me as being hip or edgy... and I don't think Korea really has any cool youth movements that are their own. All of their youth movements are more like old people's movements... it's like hanging out with right-wing preppies, brain-dead gamers, math-smart drones, wannabes and hipsters who communicate with confusion, hesitation, awkwardness or drunken sleazery. And melodrama... don't forget the melodrama.
If you go to Tokyo, that place has style... and they make it their own. If you go to New York, it has style. Toronto is soulless but at least it tries. London has its own thing. Seoul is still trying to get there... or maybe I'm just missing something, and if this is the case, please tell me where to find it!