I'm usually solo.  I have a couple of friends that i ride with and feel comfortable with.  I'll ride in a pack of 2 or 3.   Of course, if the wife is up for it, we go two up. 
I have been in larger packs where there's one or two who's ego's are bigger than their bike and let the drama begin.  ( not formal rides, just a large neighborhood group)
However....yesterday, a couple of RKC's joined in during my morning scoot/Church.  We talked at lights, had a soda at a corner store, shook hands and went our own ways.....good people, good ride.