just curious here... do COS pre-board? 'cause if a COS had a C boarding pass and was unable to pre-board, there is no way to guarantee two seats next to one another unless they ask other passengers to move (and the others have the right to say no)
also, both my dh and i are pooh sized people and i've considered buying one COS seat... can we then "share" that extra seat? (although we've flown swa a dozen-plus times and have never needed a second seat as we don't flow over and can sit comfortably w/the armrest down... but just to have the extra space might be nice for a longer flight (i.e. NY to LV)...
also, can you buy your COS seat w/a ding fare?