Powerleveling with a friend

[iruleatants]

I have a level 70 friend who owes me level 70 as well...

He has both a shaman and a warlock, and so I want to know where, and how is the best/fastest way to gain many many levels.

[MrDeath]

For a shaman enhancement is the way to go while leveling.

For a druid feral is the best overall to level fastest.

[iruleatants]

No, you misunderstood.

He has both of the level 70's (a shaman and a warlock)

What I need help finding out, is where and how is the fastest way for him to powerlevel my druid to 70.