Arcane AoE is so low and complex there's really no wrong way to AoE like Aquamonkey said (except blizzard xD)
I usually dont even bother on trashs, I just NT 2/3 mobs, get to 6 stacks and AE like a madman . (i'm haste, so ABarr isnt a viable option)
Now, on boss, that's different (Windlord comes in mind). I use glyphed LB then single target the adds down.