howdy oldtard and welcome to the forums!

personally, i use focus based macros. this allows me to just select a target on my active wow and fire. all my alts get the key and trip the associated macro... and if the power is a targeted power, then they would target the same thing.

the macros generally look like this:

/cast [target=focustarget] fireball

and my follow macro looks like this:

/follow focus

my assist is:

/assist focus

i also generally replace the melee attack macro with this:

/startattack [target=focustarget]

this helps because the default attack option is a toggle... and could get toggled off easily (i tend to spam keys when playing... or at least double tap)

the nice thing about this setup is that i can change my leader/active-targeter by using a focus macro. ie:

/focus joe

this would be on the same key for all wows and when i hit that key, joe becomes the targeting character for all my alts.

you can also take it another step by using the same keys for setting focus as your pip swap hotkeys. this would allow you to not only set the new leader, but you would be doing it as your new leader's wow window moves into the main region

i hope that makes some sense. if not, please feel free to call again (i'm overly introverted and love chatting with multi-boxers )

good luck and welcome to the addiction,

Rob