My 2 cents: I like the idea of using locally sourced materials as much as possible for all phases of construction. With all the problems related to oil based transport, this can be more sustainable. If the materials are local it is much easier to track down how they were obtained; ie: were they obtained in a responsible manner? Also, aesthetically, local materials simply tend to blend in to the natural environment better than "exotic" materials. For example, a log home looks strange in LA. And an adobe home looks even stranger in Alaska. As an amateur owner builder, local materials can be appealing for several reasons - simple, cheap, efficient, and attractive. Possibly quite labor intensive however (strawbale, adobe, cordwood masonry, etc) So, for the NW use lots of wood - for the SW use lots of soil (adobe).