I really like the look of a corner "wrap around" mantle surround. On some occasions the fireplace is best "bumped out" into the room because it cannot be pushed into the room behind. In this case a wrap around mantel surround is an nice way to enclose the bumped out fireplace. Visually it becomes a more prominent feature in the room. Secondly, there is more mantel shelf space for pictures and nic-nacs. Thirdly, bookcases can be incorporated around the mantel provided the "wrap" doesn't return completely to the rear wall. But visually, it offers the most stunning mantel surround of the other possibilities, in my opinion.