My class is in two groups of ten. The first four pairs face each other and the last pair at the back of the room faces the front making a capital T shape...This works really well for me because so much of my day is group work. I have enough other space, Horseshoe table, writing center, math center that I can spread them out for assessments.
It is chatty this way, but as long as they are talking about the lesson I think chatter is okay during appropriate work times. After all when was the last time you saw a group of adults at their jobs all doing the same thing but working silently...