If you are looking to purely maximise DPS and dont care about buying reageants etc I'd say:

1) Palla/Warrior: BS + Eng (Epic Goggles and boots, poss chest with warrior)
2) Healer Shammy: JC (various trinkets, necks and special gems), Ench (Ench rings healing power)
3) DPS Shammies: Eng - (Epic Goggles), LW (Netherstrike Set)

This would be a pretty expensive way to do it though, with no gathering profs, particularly for 3x375 Leatherworkers.

My setup is:

Pally: Eng/Ench (will swop the Ench for mining when I can be bothered)
Sham1: Skin/Mining (will drop mining and take LW)
Sham2: Tail/LW
Sham3: Ench/LW (the healer)
Sham4: JC/LW (Probably would have made a better healer, but no biggie)