Yeah with a priest you're not gonna be able to pull off significant "AoE boosting". Sure there's always shadowform+Holy Fire, Shadow Word: Pain everything, then butting out for Holy Nova, but it's not the same. It's gonna hurrrrrt.

I've done it with a Shaman, in the old days, but the problem is if you're using Fire Nova totem and Magma totem for AoE
damage you have to make sure to damage each one yourself. Otherwise it's just a pet-kill and no one gets XP or loot. Also since they changed Stoneskin it wouldn't be as useful (it used to make it so scrubs only hit you for 1 damage at a time)

Mage could work - there's thousands of videos out there on it. Fire or frost, either way; fire has that thing that gives you fast feet when you're hit, and frost is of course AoE madness.

And unless your 75 Rogue has Fan of Knives (I forget when that kicks in) I wouldn't bother; it'll take too long and your cool cooldowns won't be good enough to make the time worth it.

So I'm afraid you're stuck with the paladin, friend! But it better be prot spec, so you can make use of your Blessing of Sanctuary. That is your best option.