Any combination of only 2-3 classes I would hardly call "The best pve setup". You'd clearly be specialized in one area (no cc/all nuke for example). I have a hard time seeing a pally/shammy team going very far in heroics for example. Sure you'll probably be able to finish most heroic instances eventually, but it will take alot of time and alot of wipes. For instance, my first trip through slave pens heroic took less than an hour. In crappy, freshly-dinged-70 gear I might add. You can get away from this problem if your tank is your main character in a raiding guild and has 20k armor and health of course. I recommend the setup I have myself naturally. Pally, lock, shammy, mage, priest. You just have tons and tons of options, and you can take on anything, even in bad gear.

I must admit I have put my pve team on hold for a while. Playing the shammy team is just a total riot, and I can not WAIT for level 70, which is right around the corner now. Ellay, I'm coming for you