Well for meteors i always position myself to take the center meteor so i know that i can heal the MT from where i am at all times. Most of the spawns will have one in the middle the only time you need to move is during the cloud phase and then the Tank is fine since the boss is too busy sucking in clouds. There is nothing to do for Healers so it's best in that phase they handle the 3 meteors as they spawn between the 6 of them they can cover the room. I think they are only Healer specific for that phase I'd rather DPS kill clouds than chase meteors around the room if they can.