Our LR has about the same dimensions as yours: 12' x 20', and has some of the same issues. It is a very difficult room. And we really only have one solid wall. You see the long wall, with the fireplace in the center and glass on either side. The opposite long "wall" (behind the sofa) isn't a wall at all, but is open to the rest of the great room (see the floor, the cork is the LR and the pavers are the "hall"). You see the one short wall which is mostly glass with room for a small bookcase on the 3' of wall that is there. The wall not shown is the solid wall and has the TV canted out from the wall (corner of TV table is visible in pic), sort of in the corner like your TV. We tried various options with the furniture lined up straight. But it really didn't work for TV viewing, which is primarily what happens in this room. So we wound up with the sofa angled toward the TV, and DH's chair/ottoman at the end of the room. The club chair in the bottom left of the picture isn't great for TV viewing, but works for visiting. This picture isn't that great, but I already had it in my PC, so . . .

Eld Thanks for your advice. These were taken during the day but it was a gloomy day. The windows are large but with the balance and thickness of the curtains they limit the light in. Those windows do face the front of our house so I do want to be mindful of that. I thought slate because it pulls in the color from the fireplace. And I think I’d prefer to not have an accent wall in this room.

Before you can decide on seating you need to design based on a balance of what you need every day, what you need when you have guests, how often you need the additional seating and the activities that will be done when you need the additional seating. Example: Typically I have 2 people watching TV or playing board games in the evening. About once every two weeks I have 4 people. A 5 person sectional with an additional chair works for both board games or TV. About once every 2 months I will host dinner for my siblings and spouses - then I have 10 people, but the girls usually hang in the kitchen, dining room and the guys go watch TV. Still works. About once a year I have the whole family over for some kind of function. That will be 30 people. I didn't plan my seating for 30. I have a couple of rooms that have seating and we end up a bit scattered. I have enough seating if people use the livingroom, dining room, sitting room and I pull extra chairs that I have in the bedrooms and store in the basement. We just kind of muddle through. In the two years that I have lived here I have not once needed more than 6 seats for watching a movie. My sister entertains a lot and has a large number of guests at one time on a regular basis. She has a great room with a dining table that seats 12, bench seating under her window wall that butts against her corner fireplace, a 4 person couch with a chaise plus 3 recliners and another small bench that she will place in front of the fireplace and an ottoman that can go in front of the TV for addional seating. She also has several shallow boxes that fit over her TV so that it looks like wall art instead of a TV. Knowling your needs really helps define the amount and type of seating you need.

Thank you all SO much! Really wonderful to read your suggestions and get input. Much appreciated. And makes me feel there is potential for this space. I never considered a bigger rug, but will do so now as that seems to be a repeated suggestion. We will also take another look at the the height of that mirror on the side wall (above the mantel is a actually a large framed photo that I blacked out for this post). We did experiment with turning the dining table the other way, but it didn't feel right and seemed to block the openness of the sliding doors. And I was leaning towards an upholstered bench behind the couch (for a casual spot to sit with the added bonus of storage for blankets inside), but perhaps that would be odd? Again, thank you all. Keep the ideas coming!