Link below has directions for posting pictures here. It will help everyone to see your room dimensions and layout to help you with your furniture placement. Here is a link that might be useful: How to Post Pictures

Well, if you watch a lot of tv, then I'd make a main furniture grouping around the tv/fireplace and just put a couple of comfy chairs with a small table between, either to each side with a table in front of the fireplace, or facing each other in front of the fireplace with a table between. Just a little reading or wine sipping area. like this: If you mostly gather without tv watching then I'd do the opposite and put a couple of chairs on the tv side. You could think about using a backless chaise/bench as a piece of furniture between the areas, so people could face either way or lie down to watch tv. Like this: If you don't use the electric fireplace, I'd still think about mounting the tv lower, in front of the firebox and putting some nice art above the mantel, for more comfortable tv viewing. It's a challenging but beautiful space!

I don't see how putting a sofa facing the DR and the TV on the wall segment between them allows for decent viewing. I see your two options as (1) putting the TV in the corner (not necessarily on the diagonal -- a 65" TV is generally a little less than 60" wide -- doesn't leave a lot of space, but it can be placed flat) or (2) putting the TV on the wall between the window and the DR and floating a sofa opposite the TV and in front of the stairwell wall with a walkway behind it. I would probably use a sofa or sectional facing the sliders with the TV in the corner and a console or sofa table along the back of the sofa to give a landing spot for the DR and a transition between the rooms (most sofa backs just aren't that special base for a reading lamp too). You say you lean contemporary and the space in that corner is limited, so I would consider a non-traditional option for the TV console. This one is a lot less bulky than a traditional cabinet. It could place the TV flat or angled a bit without being obtrusive. We have a FR with an open end and lots of doors and windows like yours and the only real solution for us was to put the TV in the corner. We had a cabinet for a long time and more recently got the easel (ours is the black, which is a stain so you see grain and it comes off more charcoal than heavy black like a painted finish would be). I am so much happier with it. The components all sit on the bottom, we got charcoal grey flannel baskets for the rest of the shelf space and a cord storage box to contain the power strip, plugs and help control the cords. Once you get decide on the TV and sofa placement, the rest will fall into place.

sectionals and tvs over fireplaces are rarely comfortable. tvs hurt your neck and sectionals are difficult to work with and do not provide as many seats as you think they would. I would do 2 full sofas shaped like and L. Have your L face the 9'9" wall where the tv is. I would then have a couple chairs over by the fireplace with a small table.