I have found this to be effective:

Code:
/castsequence reset=60,target Seal of corruption, Judgement of wisdom, Holy Shield, Judgement of light, Holy Shield, Judgement of wisdom, Holy Shield, Judgement of light, Holy Shield, Judgement of wisdom, Holy Shield
/use Coren's Lucky Coin
/startattack
Basically, the seal of corruption on every new target means it rarely ever runs out, though I suppose it's not the most mana efficient. I used to just have /cast Holy Shield up first so it would always proc, but I noticed some issues with it on one of the recent patches, so I went to a loooong sequence that just alternates judgment of wisdom and judgement of light

The Coren's Lucky Coin can be replaced with Gnomergan Auto Blocker if you have that... but it has a 2 min CD, and lasts 20 sec... this arrangement allows it to pop every time it's up as long as everything else falls through. In practical terms, I use explicit keys for my pull and situational stuff (consecrate, exorcism, Holy Wrath, etc, and I have a "need more aggro" button that is just /castrandom Hammer of Righteousness, Shield of Righteousness that I start spamming if my slaves are creeping up on the aggro meter.

I ALWAYS put /startattack at the end of my spam macro so that if everything is on CD or I'm OOM, it at least makes sure I'm hitting SOMETHING

I really like some of the ideas here and may do some adjusting... this was just me sharing what has worked so far.