In general, most people find these to be (easier to harder)...


Boxing a tank:
Paladin > Druid > Death Knight > Warrior

Boxing a healer in PvE content:
Holy Priest > Druid = Disc Priest = Shaman > Paladin

Boxing a healer for PvP:
Paladin > Priest > Shaman > Druid




For PvE play, some suggested teams (play whatever you like though):

Pally Tank + 3x Elemental Shaman + 1x Holy Priest.
Pally Tank + 3x Elemental Shaman + 1x Warlock (any spec) or Boomkin Druid.
Druid Tank + 3x Elemental Shaman + 1x Resto Druid.
Druid Tank + Arcane Mage + Warlock + Elemental Shaman + Holy Priest.

The basic formula is Pally or Druid tank (easy to macro, drive with this toon and essentially mash one button and position/face the boss as desired)...
Go with a non-Paladin healer, as Disc or Holy Priest and Shaman and Druid are fairly mobile and have fairly strong AoE heals...
And any three ranged DPS that you like, with Elemental Shaman being easy to macro and providing strong buffs via the totems.

3x Elemental, can function as your healer, instead of having a healer class.
If you go that route, either a Boomkin or a Warlock will increase your spell damage via (Earth & Moon, passive from Druid DPS.... or Curse of the Elements, from any Warlock spec).
You could also dual-spec one of the Shaman, to be Resto and Elemental.

Melee classes can work for the 3x DPS if you want.
But they're a bit harder, because they'll get hit by point-blank boss abilities or boss cleave attacks etc.




For PvP play:

5x The Same Class, is generally good.
4x DPS (especially ranged) with 1x Healer, is generally good.


5x Elemental Shaman.
4x Elemental Shaman & 1x Boomkin Druid
3x Elemental Shaman & 2x Boomkin Druid

1x Holy Paladin & 4x Frost Death Knight
1x Holy Paladin & 4x Ret Paladin
1x Holy Paladin & 4x Enhance Shaman
1x Holy Paladin & 4x Arms/Fury Warrior
1x Other Healer & 4x (One of the above).

5x Feral Druids
5x Ret Paladin
5x Frost Death Knights
5x Hunters
5x Warlocks
1x Healer + 4x (One of the above).




During your RAF, get a whole lot of combos to 80th.
Even if you're not sure what you want to play, it opens options down the road.

You might have zero interest in Mages now.
But spending 12-15 hours, over 3-4 days, to get them to 80th during RAF...
Is going to be preferable to spending 50-60 hours, over two weeks, when you decide to do a Mage team two years from now.
(Not saying a team is 12-15 hours or will be 50-60 hours either, but the relative time between the two is close enough).

It doesn't hurt to have a lot of class combinations.
Those are teams you might play down the road.
You could RAF level 5x Hunters, 5x Druids, 5x Priests, etc...
And then once they're max level, decide what to mix to make your teams.

Having a lot of characters, lets you go Alchemy on a bunch of them too.
And that is very easy passive gold, via transmutes.
I made 800,000 gold, in around an hour a day for two months, near the start of Cataclysm.
Mindlessly easy, and I still have around half that on the main server and 100K transferred to Magtheridon with the Pally & 4x DK team.