What is the most interesting area to live and walk walk in Bangkok and why? Nana is interesting as a zoo, but let's not include it in our discussions.

I would say parts of Rattanakosin rank amongst the best areas for walking as the area developed in a time when that was the way to get around. I would favor the the less touristy areas such as those around Talad Nang Lerng. Many of the smaller streets are tree lined and bracketed by century old shophouses and are great places to spend an afternoon just wandering around. The big down side (and the reason I wouldn't live there) is the lack of public transit. I can't imagine not living within walking distance of a BTS or MRT line.

I would second Rattanakosin or perhaps immediately north in Dusit. It's old with more of a grid pattern for easier and most pleasant routes for going from A to B. Most of Bangkok feels like it was laid out by a snake on LSD -- you can't really get anywhere unless you suffer quietly walking along 4-lane street that is choked with traffic and pollution. The sois are quaint in their own way but most don't go anywhere. Bangkok has to be one of the worst cities for walking on this planet. No grid pattern, too hot, too polluted, fewest parks per sq. km of any large city in the world, few trees (hence little shade). Just a nightmare really when you get right down to it.

Thonburi can also be nice for similar reasons -- especially the area across the Memorial Bridge. Lots of smaller streets without too much traffic. I had a good ramble over there.

I'd be interested in hearing about any others that I might not know about. Canals often have walkways next to them and those could be alright but many of the canals smell so bad you really can't walk there for any length of time. The elevated walkway between Lumpini Park and Suk soi 10 suffers the same fate. The part between Suk soi 2 and soi 10 follows a very smelly canal/pond/open sewer. Just brutal. The walkway was a good idea, but it didn't quite make it.

Speaking of Rattanakosin: http://walk.tourismthailand.org/tour.php

Technically not it Bangkok,

http://www.crankylittlemonster.com/blog/blog123_bang_krachao.html

People complaints that Bangkok doesn't have enough green space of parks, here's a little area that's undeveloped, unspoiled and has great views of the city

Bang Krachao on the other side of the river opposite the Port, there's a ferry that takes you there from a temple, or you can drive up from Samut Prakarn Side