Hey John, I did my first long trip, Denver to Yuma, AZ a few weeks ago. Went through Flagstaff both ways. Took the interstates, (25 to 40) on the way there, went through Durango/ Four Corners on the way back. I'd of course recommend the Four Corners route. Both ways were HOT once you get south of Colorado and into Navajo country, scenic though.
Getting there in one day might be a butt-kicker just because of the heat. Once you get up to Flagstaff though, it cools off A LOT. Too bad I gotta work, I'd join ya!
