Left the car near the Bright Angel Lodge and took the shuttle to the North Rim. 5AM shuttle to the N.Kaibab Trail Head...we were the only ones on it. The first hour or so in the dark...3 hrs. to Cottonwood Campground, and 6hrs. total to Phantom Ranch. About an hour rest there...crossed the Black bridge at noon. Up, up, up, on the S.Kaibab...we were very slow the last two miles...but reached the parking lot at 4:30PM. Shuttle(s) back to the car, dinner in Flagstaff, and made it home to Phoenix by 10:15PM (38 hrs. elapsed!).
Worth noting: this was a physical reach for us (none of us in shape, and my wife and son are very occasional hikers)....but a great experience.