I thought this was a helpful description of the ideal flow of conversation when having a large group over for dinner. This is a little high-class for us and our kids, but the idea is solid.
From the etiquette column in January's edition of The Atlantic Monthly:
"I don't know the right protocol, but I do have a sense of what works best around tables in Washington. That is that you leave conversation unmanaged for the first course, maybe the first two. There will come a time, however, when people naturally want one-table conversation. The disappointing dinners are the ones in which the host missed that moment to convene everyone and, instead, people leave without the benefit of gearing each other on the biggest topic of the hour." David Bradley, owner, The Atlantic Monthly.