I have tried:

Pally - Priest, works GREAT, I can gather a bunch of mobs and bam they're dead. Don't try this before you have consecration though. I specced Ret - Disc

Warrior - Druid, a little bit difficult because Warrior lacks AOE tanking capabilities. But that just means I have to pull smarter. I can still take 5 mobs of the same level, but not 10. I specced Prot - Balance

Death-knight, Priest: (starting at level 58 in outland): again, great. I rarely used the priest, just need her for little healing.