In my limited travel experiences, nothing epitomizes urban more than Chicago.  Even more than the towering heart of the city in downtown, I think of the vast and varying neighborhoods that provide the blood, the life to that heart.  Driving through these neighborhoods quick glimpses of the different cultures, ethnicities, and economics that criss-cross and collide throughout the city, but putting your feet on the ground and walking the streets is the only way to truly appreciate this type of environment.  There is very little space, save for parks and playgrounds, or some occasional empty lots.  Everywhere is occupied, and if it isn't, it soon will be; people and commerce are seemingly at arms-length with every step.  Neighborhoods, homogeneous in their contents and inhabitants, or a the cultural and commercial equivalent of a Pollock take turns in your travels.  Some neighborhoods act as battlefronts for old and new.  Classic neighborhoods bookended by million-dollar condos, with gentrification's tendrils reaching in all directions.  Homeless or hipster?  Who knows, they're both just as likely to have a beard and a bike.  For all the life that these neighborhoods offer, too often, many also offer death.  Segregation and neglect are the downside of some of the sectioning off of the city, and that lack of space I spoke of.

I imagine New Orleans is much the same, maybe just a little slower and damper; that's just how the south comes off in the media or in person.  There are different mixes of cultures, of course, but the battle of old and new, commerce and community, life and death remain the same in the city.