I've 5-boxed all of the normal dungeons, killing every boss, with my mixed team - pally tank, priest healer, mage+hunter+warlock DPS.

For me, the final boss in Lost City of Tol'Vir was the worst by a long shot - nightmare the way he bounces everyone all over the place at the phase transition and collecting the group is a pain. If he bounces anyone off the roof, it's almost certainly el-wipo

However, IMHO, the normals were a lot easier than I remember LK normal dungeons being.

I'm just after my last couple of upgrades before I start on heroics.