An adventurous and rightly popular variant to the classic Chamonix - Zermatt Haute Route ski trip.
If the Haute Route through Verbier doesn't sound adventurous enough for you, this is a ideal variant to spice things up. It takes in the legendary Plateau du Couloir day, which is both serious and stunning, but can still be squeezed into 6 days (weather permitting). For the sake of comparison, here is the guidebook to the Verbier Haute Route.
It shares roughly half of the terrain with the Verbier Haute Route but deviates during the middle section of that route to seek out some more challenging terrain. As with the Verbier route it takes you through some massive scenery and to some lovely mountain huts.
If this route still isn't enough of a challenge, why not check out the St Bernard variant?