I remember reading an article in MBUK (might have been a different mag) a couple o years ago, and they were trying to descend the height of Mt. Everest in 24 hours, without covering the same trail twice. They did this in Chamonix, by just going up the chairlifts and cable cars and coming back down.
Also from when I went before that article, you could do some very good high altitude rides, ie catch the chairlift up to the meadows above the treeline, and then just follow the contours along. And when you wanted to drop back to the town, there were a myriad descents to chose from, from 40mph fire road screamers to technical singletrack. The trails are so good there that you don't really need to plan, just pick a different chairlift every day and ride trails which look good when you get up there