Ultimately, from what I've seen here {Boston, NYC, SF, Atlanta, Dallas, LA, Las Vegas, etc} and quite a bit abroad {London, Paris, Warsaw, Taipei, Seoul, Dubai, etc} -- there is {or at least there was} only one city with true Night Life if you define it as being virtually indistinguishable from evening life
That City of course was the pre-Katrina New Orleans and specifically Bourbon St. in the French Quarter.
Neither New York or even Las Vegas could compare with Bourbon St. --Where else could you walk down the street and then hang by the open walls of a club listening to live music while sipping a brew or a "Hurricane" and then stroll back the other way down the street a couple of blocks grab some gumbo on a paper plate from a "hole in wall" grab another brew from a bar kiosk and then while walking closer to the buildings {for stability?} nearly get kicked in the head by a Blond swinging out through the "window" of another kind of club while she's sitting a red velvet trapeze wearing high heels and some red velvet ribbon, a few tassels and not much else
Then later in Jackson Square, near St. Louis Cathedral, you can collapse against a potted palm tree while wearing a top hat and tails
Later as the Sun is coming up try to sober-up with some cafe-au lait and Beignets at the Cafe Du Monde on the Riverwalk
Finally around 7Am you can have your face caricatured for posterity by an artist in Jackson Square -- stagger back to your hotel room and sleep until noon or so and be ready to go again
All the above was participated in or at least observed by your intrepid correspondent on more than one occasion in the Quarter
Not sure that it belongs in any other place than NO
Westy