Oh btw, about the warrior versus other tanks. Paladin is probably the best choice for boxing, since they macro easily. You have to think/position a bit more with druid/dk/war, but nothing gamebreaking. One thing to mention though, is that your three dps are all ranged spell casters, which means the warrior only brings commanding shout to the team in terms of buffs / synergy.

A druid would bring GotW, but you can item-buff that (drums of the wild or whatever), however an unholy DK will give you spell damage taken debuff and some utility: death grip, which is great for caster pulling, water walking, which is nice for questing etc.

In terms of min/max, DK is probably the best choice - in terms of ease of play, I'd go paladin. I dont see any real good reason to go warrior though, except that you'd be a "classic" trinity group.