The scale of your furniture will be immensely important. Loft/apartment sized pieces will save you a lot of space and heartache. Personally, I would try to use the kitchen as the formal dining space, making use of the long wall for a settee, a trestle table and chairs. A round dining table is going to require 36" of space all around for chairs to scoot out and to navigate around. Taking advantage of the wall and a slim table will make a big difference. Then you'll have all the rest of the space in the front to make two seating areas; one for TV up front where there is a wall for the TV on a credenza, a 3-seat sofa and a chair. The middle area by the stairs would be for cocktails, conversation, reading with a nice pair of chairs, floor lamp and area rug.

Ideas- Add maybe 3-4 prints down the wall to the right of the fireplace that are personal/meaningful- and sophisticated (Not big box typical) or some tall narrow piece of furniture or plant kind of a thing. The wide fireplace and big wide tv make the room seem low, but it could be the pictures. Just want to make the room seem taller. Smaller coffee table. Too much big rectangle stuff in my opinion. But, a round coffee table can take up a lot of space- so careful. Going to add a rug? Tall and narrow items at the ends of the fireplace to help cover the tv cords. I think you could squeeze one chair in but not sure about two. Can you tape off the floor for sizes to see how much space they would take up to see what you think? Add some color and texture to your accessories, but not too matchy matchy. Again, personal and sophisticated. And not a bunch of sayings! Oops- I maybe just gave you more thoughts about what not to do... Nice that you were able to open up the space!

I think you have some good ideas. When you pop off the corbels you may be able to touch up with spackle and paint. If the gap is too wide to fill with spackle you can use a small trim piece to fill it. I would do the same thing with the fireplace surround. Just pop it off and see what you have to work with. Installing a single mantlepiece is not that complicated. I would take off the frou-frou over the top of the dining room entry as well. And paint your vent the same color as the wall color so it will recede. Are you painting the room gray? Do you plan on changing the carpet as well? On my monitor, the cool paint and the warm carpet aren't playing well together.

I don’t know how to take your plan and add furniture to it 🙃... so I will just explain how I would place your sectional. I would float the sectional where the back of one side of sectional is to dining room and the back of other side, is to the kitchen. That way your window and fireplace are the view from sitting on sofa. I think this would be an ideal set up for your space. You could still add a chair in the corner between window and FP, or place an additional chair directly in front of window, without obstructing a lot of your light. It’s a great open floor plan, congratulations on your new home.