Some food for thought on the urban (suburban) vs. rural sustainability question -
http://energybulletin.net/node/3757 .
There are pros and cons to living rurally vs. "in town". My biggest concern is dependence on automobiles. If you need to drive (to work, school, the store, etc.) on a daily basis then I don't think your location is very sustainable.
I think finding the right community of people is very important and that can happen either in a city or in the country.
FWIW,
Tim