I approached Gannett Peak from Pinedale. The road to the trailhead is on the right as you enter Pinedale from the south. The Forest Service office (307-367-4326) is at the same intersection. I chose this approach because I could get close to my campsite on horseback, and I wouldn't have to do much elevation gain with a heavy pack.
I booked a guide and horse, a mule to carry my gear, and a horse for me to ride for the trip in. I used Bald Mountain Outfitters (http://meek.sublette.com/Baldmtn, email@example.com, 307-367-6539) and was very happy with them.
On July 30, 1998, Bald Mountain took me fairly close to Lower Titcomb Lake. The ride took about six hours, mostly in the rain. I carried the pack another two hours to get to camp. I arrived at camp in just one day and was fairly fresh. Without the horse, it would have taken two days and I would have been half-dead from carrying the heavy pack. The horse is well worth the price. I camped above Upper Titcomb Lake at about 10,800. The ground accepts tent stakes, so a freestanding tent isn't absolutely necessary.
On July 31, I woke up about 4:15 AM. The sky was full of stars and I could see two headlamps on the way up Dinwoody Pass (also known as Bonney Pass). I left camp at 5:15. The snow was just soft enough for kicking steps, so I only used crampons near the top of Dinwoody Pass. At the pass, I took off the crampons and plunge-stepped down and across Dinwoody Glacier.
The easiest route went around the right of a huge buttress at 11,700 and then west through a few crevasses near the north edge of the Dinwoody Glacier. The crevasses required a bit of careful routefinding, but they weren't a major obstacle. I then climbed an obvious snow-filled couloir, which is visible from Dinwoody Pass. I followed the steps of the climbers I had seen earlier. The couloir is only 37-40 degrees, so we all kicked steps in the snow without using crampons. At the top of the couloir I stashed some of my gear and wandered up easier snow and rock toward the summit. I met the other two climbers on their way down, talked with them for a few minutes, and reached the summit about 9:15. Don Jacobs calls the route I climbed "Route 4: South Ridge."
After a short break and a few pictures, I started down. The weather was good, but clouds were rolling in, and I didn't want to be on top of Dinwoody Pass in a lightning storm. I caught up with the other climbers, passing them as we picked our way through the crevasses. The snow was firm enough to support my weight and soft enough for kicking steps. I made good time and was back at camp before noon, just as it started to rain.
I ate, dozed, and sorted gear until the weather improved and my boredom outweighed my fatigue. I decided to pack up and start out. As soon as I started hiking, the weather deteriorated. Within five minutes, the clouds dumped their entire contents on me, I was soaking wet, the ground was covered in hail, and the sun was shining again. I made it to Island Lake with just enough daylight to set up camp and eat dinner before dark. I was totally exhausted.
I spent most of August 1 carrying my pack back to the trailhead, mostly in the rain.
The main requirements for climbing Gannett Peak are good basic mountaineering and backpacking skills, good physical condition, tolerance of thin air, and decent weather. While Gannett is certainly a lot of work, it was much easier than I had expected. I only used crampons for a short distance on Dinwoody Pass, and I never bothered using the ice axe. Despite what Don Jacobs says, I call that a walk-up. Just be careful not to fall in a crevasse.