I have the pally, priest, mage and shaman leveling up to join my main (70 lock).

Right now, they are just being boosted so limited real world experience. As much as I want the priest to be shadow specced, I think she'll end up staying Holy. I think in higher end instances I'll end up wanting/needing the best healer (which the priest remains). Shammie won't be a slouch in the DPS department and as you've mentioned has some totems that will help the party.

I'll be following this thread too.