In some of the north side burbs of Chicago I saw some modest homes with some immodest prices. I was told that they were "teardowns", and the price was actually lower because of the presence of the modest house. And in the less-than-year's time I've been near the area, I've seen existing homes razed and new, huge homes erected on the spots. I guess that means that people really like living there.
I won't be doing anything like that soon, but if I did, I'd take a close look at this. Check it out and follow links from there.
Certainly some will argue that the resulting house isn't "green" enough. No doubt there is more room for improvement yet. But these improvements usually face stiff appearance, cost and convenience barriers, and we shouldn't let the best be the enemy of the good.
Most of us will probably be backfitting older homes, where there's much less flexibility in the design. But you can always put in more insulation, tighter windows, better hot water heaters or even tankless varieties, attic fans, better weatherstripping, awnings, better drapes, etc.