Weatherford Trail - San Francisco Peaks

This hike travels up the side of the San Francisco Peaks and can be as hard or easy as you want to make it. To get to the very top of the peaks (12,633 feet, the highest point in AZ) is about 20 miles and will take all day (10+ hours) but it's an up-and-back hike, so you can turn around at any point, once you'vec had enough. It is a steep but rewarding climb, as the views get more and more spectacular as you climb up the side of these mountains.
To get here, take Highway 180 north out of Flagstaff. Turn right on Schultz Pass Road, and continue 5 miles up this road to the trailhead and parking lot, which are at Schultz tank. Park on the right and head off on the hike just across the road. The trail quickly begins to climb, and in a mile and a half you'll reach the Aspen Spring. You can choose to make this hike a short one by turing around here, or continue hiking on the trail to the right. After this point, the trail really starts to climb the mountains. Remember to be safe and reasonable about deciding when to turn around. It's easy to convince yourself to just go a little farther, but every step up the mountain is another step down and you do NOT want to get caught up here after the sun has gone down. So be safe and enjoy this terrific hike!

Thanks to Cosmic Ray for the description and directions.