[DamnthatDavid]

Personally, I agree with Carni on the whole race class type, but that would be bloody hard to pull off. So why not just modify it for the entire alliance/horde conflict. But give them the option of going "Hero" class. Make it easy to get, but explain that it takes more skill, and more time to use. Levels 64-70 would be the hero exp levels (if you choose) and you level 6x slower.

Horde War: Blademaster
Alliance War: Knight

Horde Warlock: Necromancer
Alliance Warlock: Whatever

Horde Pally: Spellbreaker or Deathknight
Alliance Pally: Champion
etc. etc.

And finally give those blasted Druids the ability to turn into birds. Let them get the bonus of not having to purchase a flying mount.