I did something similar where I got everyone to 30. From 30 to 50 I leveled my casters all at the same time (relative; once I moved out of a dungeon I stopped on that toon and moved to the next and so on). I followed that by tanks, then melee. ALl the while, I would roll on other pieces of gear for leveling reasons. Eventually I got everyone to 51. At which point I went a bit more slowly and leveling each spec from 51-60 one at a time. Eventually I got all the damaging/tanking/healing classes to 60. Afterwards I picked up gathering and crafting. The Ixal quests help A LOT with the crafting leveling. Currently I'm 60 in mining and herbing; 60 in Tailoring; and rest in the 51-55 range. I may have done it incorrectly, but I didn't have to worry about gearing as much.