This is off topic, but I find the white vents in your stonework distracting. They could be minimized by painting them gray to blend with the stones.

A sofa plus chairs would be much more flexible and as noted is less bulky, but lets you shrink or expand the grouping ( by how you place chairs, tables, ottomans) over time as you get more familiar with your traffic patterns and how you like the sight lines. You can create an “ L “ on either end with a chair or make a “ C”. If you already know your family’s relaxing style is perfectly suited to make best use of the sectional , then that may be different but I think they’re often sold on basis of static “ looks” more than comfort and functionality. I think they underestimate the benefits of side tables for drinks and such - though you can use C tables for some of that- and having place for more than one person to put up their feet. Hence another reason to understand how much space you have to allow for things like that as well as pathways. Just something to think about.

I asked a similar question a few years back... the pros with in the design section helped me a lot. It is a known maths problem for designers and chickens. Did you know chickens use to be placed in a small living space, similar in how your room is done with sofas and chairs with tv and what nots. Until the problem was addressed the chickens produced more eggs. If you can't make room, take out what is cluttering up. Until you find a nice balance. I can't remember the exact formula, but take total square feet and total up the square foot foot print area of every item that consumes its area within the room's square foot area. Eventually you get the remainder of the total open area. Like chickens people need open area in surroundings. Nobody can live with 1 foot space between another, so find your comfort zone, and use the distance as a perimeter around each sitting location at the walking space. You will find your layout. I would personally look at the couch. Either one... and remove it. Then you will have room for placement

I really like the TV between the windows. You can enjoy the TV and the fire. The niche next to the fireplace is perfect for shelves that would be flush with the walls. The table would make a great game table under the window to the right of the clock. The rug you propose is okay but in this room it seems dark, something lighter would brighten up the space. For the same reason I would not get dark uphostery or furniture. A sofa and loveseat is more flexible than a sectional. I like the existing blue rug but it's a little small. I would go with that color scheme, that shade of blue and white is great in here. The seating should fit on the rug. Artwork on the walls.