I'm stuck in the same boat. I can do 1-60 in 24 hours with refer-a-friend and a level 70 helping me but then it takes another ~80 hours to get from 60-70. My problem is that I want a 70 of every class instead of a bunch of the same class. I already have done it once with 5 classes but now I'm stuck with 4 left (hunter, warlock, priest, mage) that are painful to level up (60-70).

One thing I may try is getting a 70 friend to instance tank for me and run hunter/warlock/mage as DPS and priest as healer, see how fast that gets the levels.