I ran with a team of Pally, 2Mage, Lock, Priest.

I have a warrior I'm leveling (currently 66) to see how they fit into the mix. I also leveled a second team (Pally, 3xLock, Shaman).

Here's one thing to note: Priests are squishy. Learning to box new content can be a challenge. With the team you have planned, you're going to be making a lot of runs back to the instance on your priest, simply because there won't be anyone else around you to rez. No SS, no Reincarnation.

If you are going with Warrior, and you want to do 3 DPS, I would recommend having a warlock in the mix.

However, I would actually recommend 3 warlocks. They really work well together. My original plan had been to raise the 3 warlocks so I could do 4xLock 1xPriest in PvP (hence why I leveled a new team, just to mix and match) and I had planned to try 2xLock 1xMage... but I found that my mage was really just slowing me down. With less gear, and much less boxing effort, the locks crank out better DPS in the average boxed fight simply because DoT's tick while you move.

In a different thread I spelled out how well my Locks were doing with 3xSoC - a spell mages just don't get. This spell is great because it is a ranged AoE that you don't need to target - making it very boxer friendly. It was cranking out 3k DPS back when I first hit 70, and it has only gotten better. Add to that 3xSS - which means you can have some recovery for when you are learning how to move your priest out of the fire.