On the Galibier vs Alpe d´Huez, the Galibier is not too bad from the Bourg d´Oisans side. Because you climb Lautarets before, it is very long, but the real hard climbing is only the last 8 kms, when you turn left at Lautarets. I would say the Alpe is maybe slightly harder. The Galibier is a different story from the other side, though, specially from St Michel du Maurienne. If you start there, you go up Col du Telegraphe and Col du Galibier, which are linked by a 2-3 kms descent which is only really enough to drink and eat, and the whole climb is 32 kms. It is brutal, much harder than the Alpe d´Huez (of course, how hard depends on how fast you go and on your gear selection, but that length of climb with that incline is very hard anyways. Pedro Delgado, Tour winner in 1988 and the top climber of his time, considers the Telegraphe/Galibier as the hardest climb in professional cycling. Of course, Galibier is much higher than Alpe d´Huez, so you also have to contend with much thinner air, which adds to the difficulty. The views from the top or Galibier, specially toward Lautarets, and the descent on either side, make it worth getting to the top, though! You can read a bit of analysis of these climbs on this page:
http://ridethelegends.com/routes/#tabs-1