I think an ideal group would be paladin MT, Boomkin (panzerkin) OT, and 8 shaman... ok, maybe you could swap out one shaman for another healing class (I love holy pallys as a boxer, cause they really are just a one button mash job for 1 target healing)
I really have to agree with something this simple.

ATM I'm struggling with having 2 warlocks and a mage because they are 'pure dps' classes and I can't respec them for different roles. In ZAM I got my ass handed to be by the bear boss. So I need two tanks. Well I had enough forsight to make 2 paladins but if they are tanking then who is healing? Priest, check. Shamans.... ? Can shamans be setup to fire and forget like paladins? I have yet to try it. Right now i'm kind of hung up on equipment, I don't think any of my shamans have over 1000 healing so I'm just grinding out badges but I realy don't think I can put any shaman heal on my 'big button' and expect them to last the whole battle. Even downranking. From my past experience healing with my shaman (which was back in BWL) they are alot like priests. Very nice strong heals but you can't spam anything or your dry. I'm trying to gear up my warrior now to sub out a warlock. For a new 10 boxer I do not recommend a warrior yet, although I'm still playing with macros and I think a warrior can be a low maintanience single target tank. I suppose if the goal is raiding then lots of bosses are just single targets... I'm holding out hope for my warrior as a raid tank. :P

anyway, Paladins and Shamans. Maybe throw a priest in there. The number of each is still subject to some debate. At times I'd love to have 4 paladins and 6 shamans, others just 4 paladins 4 shamans 2 priests, etc etc etc.

Priest, Paladin, Shaman. That's my holy trinity of boxing classes atm.