Rotation advice for 5 class multibox

[Poetry]

as the warlock goes I mostly bought him in for what he broght to the table

If you're looking for utility from your warlock, another spec to look at is destruction with replenishment, particularly with an all caster group. The rotation isn't super easy to optimize but can do very respectable single target dps.

mage be a better choicethan a lock or boomkin

I personally love having a mage in my group. Free food and ports are wonderful. Unfortunately in my case my warlock and mage are on the same account so I always need to choose between one or the other. Makes me want to start a 6th account!