5 Boxing druids. Deathknights in the mix?

[Ticks]

PvE mainly, although PvP I want to be tons of fun.

What else is there?

[Ualaa]

For PvE, almost anything is going to work.

The trinity is going to make things easier.
That is: Tank + Heals + 3x DPS.

You can run odd-ball configurations as well: 4x Tank, 1x Heals (4x Blood DK, 1x Healer)... 1x Tank, 2x Heals, 2x DPS (Tank, 2x H.Paladin who heal the tank but have Beacon on the DPS and self heal via Protector of the Innocent)... 2x Tank, 2x Heals, 1x DPS.

If you have a class that could spec Tank, and a different class that could spec Heals, you can use Dungeon Finder.



For PvP, battlegrounds lets you use whatever.
But Arena/Rated BGs will force more optimal configurations, if you want to succeed.

In general the fewer classes/specs the better, as you can manage them to a higher level.
I've played everyone is the same: 5x Elemental Shaman, 5x Feral Druid, etc... as well as two roles: 1x Heals, 4x Damage.