I use "mouseover" macros for all my heals, <mo> is the command. What I like to do is Target the boss so I can see its cast bar. Focus target the tank i'm healing (Shift+T). I can dps the target, switch in and out of cleric stance, and heal the party without losing my current target. I just hover my mouse over whomever i wish to heal and mash the macro w/o switching targets. I love it!

Example: /ac "Cure" <mo>