Ohhhhkay that makes sense. So I should really have something more like this?:
/ac Aero <attack1>
/ac Aero <attack2>
/ac Aero <attack3>
/ac Aero <tt>
/ac Aero <t>
And that way my target won't move from the tank, right?
Nope, you're nuking your tank again. If your tank is targeting the lowest attack number mob, you can just use "/ac Aero <tt>" This won't change your target, just cast on the mob your tank is targeting.
So last night I actually tried this style of macro out with Stone (before I saw your reply, stouter) and it worked exactly the way I wanted it to. It casted stone on the mob marked 1; if there was none, on the mob marked 2; if there was none, on the mob marked 3; if there was none, on whoever the tank was targeting; all while maintaining my actual target as the tank.
I could seamlessly switch between Cure and Stone without stopping to switch targets.
Thanks to everyone who replied, all of the info here was really helpful! WFOAssassin, if you ever find that macro library, please
Edit: I forgot to mention, the reason I don't like to use JUST <tt> is because I actually play PLD too, and on PLD I am constantly switching targets to maintain hate on the other mobs which are not the primary target. With this macro, I know I am always attacking the mob the tank wants me to attack, not whichever one he's targeting at that exact second. Edited, Oct 22nd 2013 9:56am by Raeni