That's actaully the set up I have but more as a tank so a few of my hot bar spots are saved for damage reduction/self heals instead of DPS, but a lot of the abilities would be the same.

For Staff, most the AoE is built into the staff. Wall of Elements and Impulse. But good NB abilities to augement support would be Lotus fan, Path of darkness and Drain Power. While not exactly an AoE Assassins Blade [Impale] with the Executioner passive might keep your mana up while executing thoes that didn't quite take to the AoE so well like self healers. For Ultimates, all but the assassination one does AoE so just pick which ever you like.

As for single DW, that's a bit harder since my bar is taunts, selfheals and armor buffs. But with Swallow Soul [Strife] and Bloodcraze [Twin slashes], that should be enough self healing to keep you alive in most situations. After that if you're just looking to be sneeky, Cloak and Veiled strike are the basics, then what ever you want for the last spot, usually I'd go Syphoning Strikes but that reduces damage so should only be used in your case to get Stam/Magika back and shut off again.

I'm also a big fan of Prolonged Suffering [Agony] and Crippling grasp [Cripple] as pure DoT damage since they both are really some of the most powerfull single target DoTs. But there's some issues with the utility around them.