If you want to do mages, you may want to try 2 mages and a healer, priest would be good. That way you can have heals and shield while ae'ing. As far as the rogues, 3 would be hard to position, but doable for pve. I box a war/shaman right now and it's not to bad getting them both into position for pve mele, but I think three wouldn't be fun for me.

3 Boomkin or a tank druid and 2 casters would work, stealth might be fun for getting to instance bosses and such.

As for your last option, you could roll priest/war/mage, and then if you didn't like the warrior you could sub in another mage and do your first option.