Roles for Paladin and Priest

Well, I'm on the final stretch now, levelling up my last squad, a Paladin that will be my main tank for my 4 Shaman and a Priest that will be working with my 4 Warlocks. I'm not familiar with either class and I must say, I'm finding Paladin a little .. well .. boring. I don't suppose that boring is a bad thing when you're multiboxing, as it means less problems with macros and the like. My question is, would I be able to get away with making my Paladin a Retribution build to run with my 4xShaman, or would it be best to make him full Prot? Also, my Priest, again, will it be best to make him full Holy or would he get away with going Shadow, dropping shadowform when heals are needed.

Up until now, I've been playing 1 class per team, now multiclassing is coming in and making me think more about macros and the like, I'm sure I will have questions soon :)

Thanks

Pally as prot when with shamans.
Priest as shadow when with warlocks -> don't expect to be able to instance with priest + 4 lock.

Thanks, the Warlock team isn't for PvE, going to try them out with some PvP, the priest is just to keep them upright a little longer, I hope :D

Got to say, I'm not enjoying the Pala/4 Priests at the moment. You'd think it would work .. Knucklerot just ripped me apart, oh the shame :D