What I was based on 2-box to 3-box at the time.

Account 1: Prot Warrior 70, Rogue 70, Prot Pally 70.
Account 2: Priest was 62 for the longest time as a healbot.

Then I got a 3rd account, and moved my Prot Pally there.

I rolled a Holy Paladin in Account 1, and at 60 I ran:
>> Holy Paladin, Shadow Priest, Prot Pally
Sure I can survive huge aoe pulls but the DPS was not there from the Shadow Priest (poorly geared tho)

After I got the Holy Pally and SPriest to 70, I got a 4th account and xfer my Warrior to the 4th.
>> Holy Paladin, Holy/Disc Priest (I abandoned Shadow spec), Prot Pally and Arms Warrior.
It's a lot of micro to allign the warrior to be in melee range and do his Slam + MS rotation with occasional shouts.

Anyway, I decided to power level Mages and Shamans using this setup:
Account 1: Frost Mage & Elemental Shaman
Account 2: Elemental Shaman & Frost Mage

Account 3: Prot Pally

Account 4: Resto shaman



I had my healer from account 4, and 2 dps. I paired 1 Frost Mage + 1 Elemental Shaman as I levelled up. It worked great because I was getting totems and Blizzard in my AoE instance boosting.

But come level 60 and clearing Blood Furnace, I find having 3 shamans easier than having a "level" mage in the mix. It was not long when my Shamans were levels 62 and the Mages were 60. I then decided to just level the Shamans to 70 asap and work on the Mages later.

So I guess I'll see how the mages play out since I just finished levelling the 3 shamans to 70 last night.