Make it a mixed team of all the different ranged casters. There's nothing more difficult about making different classes. The only thing you need to do is choose specs that will be the simplest to box with (frostbolt mage, for example) and build castsequences that will give the greatest utility. All of the thought and challenge is in the setup of the castsequences. Once you built a good DPS sequence for each, you don't have to think about it anymore; just push the buttons. Also make other buttons do similar things, like a button for puge+spellsteal and for interrupts, for AOE, etc. You'll have some special buttons to drop totems that only the shamans use, or to change druid forms, but it's not that hard to remember. With a mixed team of shamans, druids, priests, mages, and warlocks, (one of two of each) and paladin tanks you'll have every buff you could ever want. The only thing you lose from mixed teams is the ability to micromanage your spellcasting, but having mark, fort, spirit, int, auras, blessings, bloodpact, moonkin aura, and totems all stacked up at once more than makes up for that, and makes you harder to kill.