I ran a priest and 4 mage group for quite a while. I was completely satisfied going heavy arcane with some fire to get pyroblast.

Quad instant cast arcane barrage was just too sexy to even bother with any other spec. Presence of Mind pyro or arcane blast every 2 min was even better. And you have plenty of AOE with arcane explosion and frost nova you dont need to worry about blizzard. Free water, mana gems, and evocation means your not waiting for mana to regen.