Just one quick input, playing Pally as Tank and Pally as Healer is really two "classes" in terms of multiboxing macro setup.

I think your class makeup is actually great for PvE. Since you have some CC (Mage/Lock), and your Pally or Shaman healer wouldn't be so squishy, I'd consider respeccing your warrior as Prot.

Prot Warrior Tank
Holy Pally Healer
Shaman/Warlock/Mage ranged DPS/CC

That seems like a pretty kicking 5-man group. Work on your CC/focus macros and get to where you can have 2 mobs CCed and have the warrior tank the other 1-3...