More views of the living room! Excuse the mess:)

Have you tried floating the sofa perpendicular to the window and FP with its back to the dining room? I think the white credenza in the hallway is more of an appropriate size than the small piece you now have under the TV. You could place it left of the FP on the wall and set TV on a swivel base for adjustable viewing.

Pull your 2 chairs to be squared off with the sofa as it sits. I would then, if possible have custom bookcases built on either side of the fireplace. Instant warmth. And one of the bookcases can be built to accomodate your TV. Pull your table that's kinda floating in space over to the sofa so that it has some relation to it.

I'm with decoenthusiaste - the sofa perpendicular to the fireplace and wall with its back to dining is best - shift it towards the fireplace. Use the light / near matching chair further away / use the contrast chair closer to - and both of these angled across from the fireplace. Round table in between. Eventually, a narrow console table behind the sofa would allow for matching lamps and a sculptural piece between. This way you can look out in summer and to fire in winter - It looks like you can easily make space to walk through on the window side - Since the room is already longer and a bit narrow, I would not narrow with built ins - I like this traditional feel. Would hang television on swing arm and put cabinet flat on wall below eventually.

Going to try moving the sofa perpendicular today. We tried the chairs squared previously and my husband felt like the chairs looked unsettled and misplaced. I think part of that is because they are so mismatched! Love the idea of built ins. We actually git sold drawn up for the room, but I was still struggling with the seating arrangement and wasn't sure if we actually needed them or if it would fix the problem. Thanks for y'all's suggestions, keep em coming!