I understand what you are saying but moving the tv to the wall with the window wouldn't work that well either.
it would be good for speaker placement but as you noticed, the room is rectangular. I would have to put the couch next to the fireplace (which I wouldn't want to do) and wiring the back speakers would be much more complicated. also, the look of the room would be much more closed off. on top of that, part of the reason I liked this house was that the kitchen over looked the family room, meaning you could watch tv while doing dishes, etc. That would no long be the case if I moved the tv.
