Started a warrior+4 shaman party myself a few days ago, first few levels are boring though and setting up was a pain. D: But you got experience with 3 so setting up should go smoothly then.

Good luck though! And as far as set ups go. I'd probablu suggest some capable tanking class. Shaman go a long way, but those movies you see of 5x shaman owning up places, are usually already geared up people. xP And tanking is quite fun to do as a main too.

They say paladins are easiest for tanking multibox, druids second and warriors third. I just like being a warrior myself though.