In reply to michael lawrence: have a look at Tignes (the other side of the Espace Killy ski area from Val d'Isere, you drive past the turning about 2km before you get to Val d'Isere.
In the summer has MTB (with lifts to save pedalling uphill!!), tenis, swimming (indoor and out), walking, a little climbing and is only a couple of hours drive from Chamonix, Anncey.
I have skiied (both for pleasure and work) there in both winter and summer - highly recommend it!!