In 1k it's tricky for ghosts, as you want to be taking 2-3 heroes really, but then you do that and you don't have enough points for your units to be viable to kill anything big and nasty, like a VLoZD with ethereal save and mystic shield ?.
I'm struggling myself with decent all round 1k lists to be honest. Being trying out 12 myrmourn, with spirit torment as general and ruler of the spirits, giving the torment midnight tome and taking shackles as a spell. The torment casts the endless spell, the banshees eat it. The torment heals the dead banshees, who now have 24 attacks at -2 rend. the torment lets them re-roll the ones, as 4s to hit is not good for such low attack numbers, and the D3 damage is decent. If you also pair with a GoS, they are wounding on 2's, and the KoSos can give them 3 attacks. If positioned well, they can unbind an enemy spell (at +3 on the unbind), to then take the total up to 4 attacks. But at 1 wound each, they are squishy and they can synergise well to put out a lot of hurt, but to get maximum output (3-4 attacks each, re-roll 1s to hit, +1 to wound) requires a minimum of 420pts of support units and spells, and that's to buff a 210pt unit!!! The only issue is that -2 rend messes with trees really well and other than characters or the BC, I don't think we have any other units that can do it, except the torment and the chainghasts, but their overall damage output would take more than 5 rounds of perfect rolls to take out a treelord.