In your other thread, you mention three or five boxing.
I'd personally recommend you go with five, but three will work.
Whichever you go with long term, its by far the easiest to build the group together.

During RAF, I'd definitely get a lot of team options to 60th.
Try to give yourself as many options down the road.
It wouldn't hurt to have 2-3 caster/ranged types (Druid, Hunter, Mage, Priest, Shaman, Warlock).
And then some melee options (Death Knight, Druid, Paladin, Shaman, Rogue, Warrior) too.
You might not play them all, but they'll let you build future teams much quicker.

I'm playing:
1x Prot Paladin + 4x Elem. Shaman.
1x Feral/Boomkin Druid + 1x Disc Priest + 1x Destro Warlock + 1x Elem Shaman + 1x Frost Mage.
1x Boomkin/Feral Druid + 1x Boomkin/Resto Druid + 3x Boomkin Druids.
4x Affliction Warlocks + 1x Disc. Priest.

I did not do Warlocks, during RAF, and leveling 1st to 60th is going to be a bit of a pain.
But they are a fun composition, so I'll do it anyway.
I've opted for being the "other" faction on these guys, so the quests will seem "new" and be less boring doing 1-80 without RAF.

Also, did not do a melee team, which I'd like to try.
I'm going for 4x Rogue and 1x Druid (Resto).
Will be doing Worgren, when Cataclysm comes out, again to keep it kind of new.
Another non-RAF team, which will take a longer time to level.