I don't know what you're referring to specifically, but a lot of what's objectionable is characteristic of modern American cities and not of any region. Are the goings-on in Atlanta, Phoenix or Dallas all that different from those in Seattle, Boston, or Chicago? I'd imagine many "red zone" cities have a wilder nightlife than Milwaukee, Buffalo or Philadelphia.
TV and mass marketing have made the country more uniform. Everyone who has a TV has probably been exposed to today's cultural rot, wherever they live.
And even in the Northeast, I'd imagine that the image is "Will and Grace" and the reality is "Married ... with Children." The image is of gays and swingers, but the reality is as often the kind of hardworking, religious, family people who were killed at the WTC.
It may be that urban America is decadent and depraved, but drawing borders to isolate the rot would be very difficult indeed.
Affluent yuppie strivers are the same South and West, North and East. The real dividing line isn't where they live, but when they have kids. You won't be able to keep them wholly out if you want to have a modern, functioning economy, and they bring their manners with them.
And even if you do, there's a trickle down or spill over of affluent decadence and immorality to those lower down on the social scale. America in the Forties and Fifties had been able to push drugs and promiscuity to the fringes of society. They've been creeping back up or down to the middle classes wherever you live, unless you're very lucky.
That's not to say that resistance is impossible, but secession or division looks like a bad bet to me. So long as people have leisure and affluence, you can't keep the initial commitment to virtue going, and things will start to creep back closer to what they are now.