I wouldnt mind trying out a Mage + Ele Shaman combo, healing, portals, free food and drink, totems, res(After wipe self res and then res), high nuking power, both have melee based AoE without mouse targeting, slowing, CC, so many tricks to help you run away.
Did i miss anything
2x Pallys are also good for double Buffs and auras (I have 5, its a bit crazy)

Umm..... I dunno, I would always want a healer in there, just to decrease downtime. 2x Warlocks could be good with drain life being used when you start getting low on health.