crumbs, I figured a lot of this out last summer, and I was thinking of how valuable the info would be, now I'm wondering what I did with it all.
Anyways, I did 4 butts and two packers, along with some wings (most of the wings didn't get cooked and are still in my fridge, so count those out). I'll bet there were 50-60 people there and we barely dented the meat. I think we figured we could probably have served 100.
don't forget a couple pans of barbie's beans. I did two big pans of them before/during the party, it worked out great because I had the meat already done so I had tons of pork and beef bits to throw into them and people could come over and see and smell the wsm in action. Once again I made twice as much (we brought over a pan home).
I'll see if I can find the thread somewhere in the forum and I'll post a link here if it contains any pertinent info.