We've just written a guide on what it's like to ride the Galibier and bit of Tour history as well, for anyone who has never ridden the giant:
http://www.polkadotcycling.com/lates...l-du-galibier/
If you are doing the Marmotte we've also done some guides on the Glandon, Telegraphe and Alpe d'huez too.