Not sure if I can give you a better combo then the DK/Rets.

I like the idea of: Enhance Shaman, Death Knight, 2x Ret Paladin, Warrior... but am not sold on so many different classes.

My 5x Feral is a very fun team, and isn't weak.. but probably won't match the DK/Ret team either.
They have a lot of toys, like Flight Form (awesome for gathering ground spawn items) and Aquatic Form, Stealth etc.
Berserk is fear immunity, combined with the trinket and diminishing returns, virtually negates the largest boxing weakness.
For PvP, I think round-robin Battle Rez will be nice too.

The 4x Affliction with 1x Resto Druid or Disc Priest, is a rather mobile team.
I wouldn't think it to be as strong as 5x Shaman, but the mobility is nice... you can dps and never stop moving, which can be fun, not to mention filling someone's screen with dots.