Lori - my mom repeatedly tells me that she "sat back" and let us work it out. I try so hard to do the same, but it doesn't always happen. I, too, cannot stand to hear the bickering and the inappropriate accusations and the getting all riled up for such a silly reason!
How about when you say to everyone - "ok. we're going to pick up the new glasses, make a quick trip to the grocery, and then will be home."
And then one after the other says "what are we doing, mom?" "are we going home after we get the glasses?" etc.
Even with four children, I think I sometimes have to repeat it 6 times until I finally say "everyone stop and look at me. This is what is happening...."