Putting the cans right over the couches will make weird shadows on people's faces when they sit down, but say about a foot in front of each couch could be good. Given the dimensions of the room and that it is square, what about just a square of four evenly spaced lights around the center, say maybe 4ft between each light to give good light to each couch? Plus the extra over the fireplace.
Where is (are) the current light(s) in the room?
