You can see a long way out here in Denver, where the mountains meet the plains. Except when there is smog in the city, the Denver air has a desert clarity. Is it this clarity, or maybe just the altitude, that has resulted in some great urban visioning in the past few years? Certainly enough has occured for the Congress for the New Urbanism to return here for their 2009 annual meeting. When I first came to Denver to explore the city, it was early in 2001, and I was on assignment to write an article on the downtown for…