My friend did a lot of AA's in the mid 80s' (85-90ish) at the dire ratkin camp in Direwind. It's a hotzone right now so definitely a good spot for some undead slaying. It's according to what level you're at at the moment?
Well, I camped my Paladin in the Hole at 71 until she had 900 AAs, but you'll probably get sick of ghosts long before I did. Anyway, imho the two first major stopping points are The Hole, which is ideal at 70 to 71 to get your first 500 AA at least, and then Ruins of Ilsalin, which you can put to similar use around 80 or so (whenever it is that the drachnids turn LB). Hole is easy to swarm with basic gear and gets easier as you AA. RoI will require a little more gearing and AAs, but thanks to the Hole you should have those. Max out all defensive AAs, slay and riposte, and go mini-swarming. No merc, if you can swing it.
Ruins of Lxanvom, Wall of Slaughter and Arcstone are other 70's options. Nothing beats Illsalin from 80-86 imo. Last Migration Hard is an option (and a 30ac shield aug) if you dont want to share RoI. Frostcrypt for 87+
Its not really any undead slaying thats worth mentioning, but IMHO the first and one of the best places to stop at for aas, is at level 59 in the hole, get you self a tank merc buff him and yourself up and go to town, with the rate that exp flies for aas at that level you should be able to grind out a ton of aa and get the basics out of the way as quick as possible as well as stock up the thirty you can have banked when you are done there and move on in levels.
