I generally do the bottom 1st then the 2nd tier and the cathedral separately. May not be the most efficient, but then again my toons don't die.

When I enter the instance I kill the first 5 mobs and then park the RAF's near the entrance to the courtyard out of LoS of any patrolling mobs. I then run and gather the whole courtyard, nuke em down.

I then move the toons to either of the 2 stairwells and gather the entire top courtyard...rinse and repeat.

I then open the cathedral door. I leave the toons on the edge of the grass right at the base of the stairs. I run in gather as many as I can which usually leaves 1 or 2 stragglers and bring them to where I opened the door and burn them down.

With this method my toons have never pulled aggro and they're never too far to receive XP.