If you were unaware of interact with target and click to move knowledge, definitely check that out.
You can have your toons (or only the slaves, if they're the only ones to receive the hotkey) interact with (ie, move towards and attack) their target.
Master targets, slaves assist, you have the melee use their IWT keybinding.

I've got a set of Pallies, who are Shockadins.
Essentially casters, not melee.

Any casting class will be one less thing to concentrate on than a melee.
Because you can cast at range, and not need to worry about point-blank-mob-aoe's or cleave attacks.
But with IWT/CTM, melee are very viable.

Since you're asking about Tanking, I'll assume PvE is the main goal.
If you drive with your tank, than any class can tank and fairly well.
You can bind the same castsequence (or two step macro) to each of the keys that your tank clicks in the process of tanking.
So if you love a Warrior (who is the most micromanage intensive tanking class), and decide you need to manage nine abilities to play them well as a tank, you could have your DPS all do their same two-step or one-step castsequence on each of those nine keys.
In short, play the tank you enjoy the most.

Multiple Shaman characters are always a favorite.
Because many of the totems will stack, and with several Shaman characters you cover most of the buffs.
They're a fun group to multibox, and are getting buffs on test realm.

I've always loved Druids, initially as Boomkins but lately as Feral.
The Eclipse mechanic sucks to manage as a boxer...
The issues for Ferals would be similar to Paladins, in that you need to be in melee.
Feral Cats are relatively simple to macro, if you want to use Mangle... but much harder if you want Shred attacks, which require being in the rear arc.
A team of Druids could be (for PvE) Feral Bear (Tank) + Resto (Heals) and 3x Feral Cats or 3x Boomkin.

For PvP, a very strong current team is 1x Healer (usually Priest or Paladin) with 4x Death Knights.
The DK's run Frost for PvP and can go 4x Blood for PvE.
Four blood tanks takes a while to kill things... but has very good survival, especially with the healer.
This team is generally driven by the healer.

Almost anything you want to run, has a good chance of success for PvE play.
The basics are generally, something that can Tank and enough healing...
Last expansion I ran Prot. Paladin, Demo. Warlock and 3x Elemental Shaman (who between them was enough healing for all 5-man content -- did everything except Oculus).