Sion will almost inevitably be a mountain stage like in 2010 when Valverde won, sorry, Antón won. The climb to Ovronnaz is near there and is quite steep, and you could do some variation on the Nendaz climbs too. And of course Crans-Montana.
What is Crans-Montana like? They climb it nearly every year in either Romandie, Suisse, or both. It's the one Soler won in 2011, and that Martin won in 2009. There are lots and lots of routes to the top; none are super-hard or anything, but some are good for pure power climbers and some are a bit more for the flyweights.