In reply to stewieatb: Ideas for some acclimatisation walks:
Get the train up to the Montenvers then walk across to the middle aigulle do midi station, it has a name but i forget it, spectacualar views of the cham aiguilles and mont blanc etc.
Get the Index lift and climb the Index, non glacial approach and 10 mins from the cable car, 5 or 6 pitches at around Severe with an easy abseil descent.
Go up to the middle Brevent station then walk up to the Brevent and either walk down or lift down
Last summer we walked up to Montenvers from the valley and went for a wander on the Mer de Glace, dry glacier with little objective danger and some interesting ladders to descend, specacular scenery!
Lac Blanc is meant to be nice but i've never been !
Or just take a book up the Midi and chill up there with a few litres of water
HTH, Pete