Downtown in any of these huge South East Asian cities can be fun for a bit but gets tiresome having everything be so busy all the time. I lived in Chiang Mai for a bit and agree that living downtown there is much like it would be anywhere, overpriced and overpopulated. Plus if you are a whitey living in those cities you will always be perceived as a tourist and will be harassed constantly by touts.
RE: Why the suburbs of Chiang Mai is a great place for an expat to live