Druid / Priest / Mage / Warlock / Shaman

The Druid is your tank. Either the Priest or Shaman is your healer. Mage, Warlock and whichever is not healer is a caster dps.
So your dps is either Shadow/Warlock/Mage or Elemental/Warlock/Mage, either of which is workable.
For in-combat crowd control we have Banish (Elemental/Demon), Shackle (Undead), Sheep (Beast/Humanoid), Hex (Beast/Humanoid).

For CC's to work best, you'd want to have a non-Focus based leadership system, so Focus can be reserved for CC's.

I'd spec the Warlock demonology, because it requires the least amount of micro-management.
Mage and Elemental or Shadow can easily use a big-button macro, for most of your spells.

You have fairly decent AoE, especially if you broadcast your mouse clicks.
Even if you don't, Warlock-Seeds, Priest-Holy Nova's and Mage is your active window for Blizzard.

I'd say the composition works for PvE content quite well.

PvP might be a bit harder, with five different classes.