Have you ever had to ride the E or F train from 6th avenue to Queens?   Have you ever been stuck in a subway tunnel with low lighting?  Have you ever gotten onto a train, with hardly any people...and wish you hadn't?   Have you ever accidentally gotten off the "wrong stop"?    Have you ever had to follow poorly written signage while transferring from one line to another...two lines which used to be competitors and so had no native inter connectivity except a half mile long, poorly lit "passenger tunnel" with moldy pools of water near the drains?   And have you ever been crammed into a train where every seat and square foot of standing room are taken up and there's nothing to hold onto as the train lurches and the doors ding and you wish that there weren't so many old ladies on the train so you could grab the next orange or yellow McDonaldsesque seat and stare out the window into the blackness as the 19th century pillars goes by?

I'm back in the boring midwestern city of my origin, in a nice house I could never afford in the "green trendy" place.  I bike to work, practice permaculture in my small but packed yard, and am slowly eco-updating the house.  Where I am now feels more sustainable to me, with a few exceptions I am seeking to address (e.g. grid electicity here is mostly nuke and coal fired).

I got this far by taking single incremental steps forward, recognizing that I do have choices-- practiced every day, in how I will live. Consciously striving for more sustainable options as I make these decisions, has been very worthwhile from a personal standpoint.

I have a hard time envisioning the 'burbs as sustainable at this time unless solar power conversion becomes much more efficient.  With their lack of grid street connectivity (bad for walking and biking transportation), isolation, and dependence on fossil fuels for everything from lawn mowing to a trip to the pool or park...  The burbs are not going to cut it well in a carbon constrained future.  I could live there since I drive a hybrid, but I'm better off closer in to the city where I don't even have to drive for 6 out of 7 days of the week.

Only in an eco-developed burb with small lots, front porches and common (not privatized and fenced) green space could be sustainable.  Try razing the old cul de sac villes and redoing it with sustainability in mind.  The burbs and their inhabitants right now are still deep in denial, I suspect when it comes to sustainability.  So they're going crazy in their wheeled cages on the highway, creeping along...  

Telecommuting should enable exurban living off the grid, with growing your own food... unless one wants social stuff that cities excel at.

We needn't go all the way to the NYC example of Jabailo's above, to live sustainably at the personal scale.

Moving toward sustainability with hopefulness, one revolution at a time.

If you're advocating for the environment, the issue is not one of whether the selfish desires of individual humans would be satisfied by certain lifestyles or living arrangements, but whether those things are in harmony with the natural world.  Specifically, does your travel require oil or other ecologically harmful infrastructure, or do you live close enough to regular activities to walk or bike?  Etc.

How about we improve public transit, create walkable/bikeable communities, and learn how to relate to people from outside the glass and metal frame of our car windows?

Moving from the cookie-cutter, highway-choked suburbs to a city I can walk and bus around has transformed the way I perceive and know the place I live. Sitting in a car never gave me that kind of feeling for who else lived in my neighborhood.