Try angling the couches in a V sort of facing the fireplace for a bit more intimacy. Or, have one facing the fireplace with the other ar right5 angles to it and bring in that chair.

Interesting house, where is it?

The biggest issue to me is lighting. All the pot lights above make it seem too dower. You might check into changing the fixtures in the pot lights to see if you can't use them as direct lights for artwork on the walls. I'd add lamps and uplighting to help brighten all the brick. I'd also want to add a lot of fabric to soften all the hard surface of the brick, so more/larger carpets, even perhaps a rug/tapestry as wall hangings.

It may not be as comfortable as you dream, but it sure looks stunning as is. The vintage couches just look right to me, but not a room that is used, perhaps. I can see how a large sectional with an ottoman would really change the feel and use of that space. GO BIG, which seems weird for me to say as sectionals are not my favorite. Love the idea of tapestries on the walls. Competing with the brick would not be easy for say a portrait. Having said that I see there is no TV. Why a sectional if no TV, perhaps four occasional chairs around a fabulous coffee table would make it a conversation room that would actually get used?

THat arched brick wall would be gone if it was my space I am sure it is some sort of support structure but a couple of posts would be my choice. I love the vintage sofas but honestly not in that space without a lot of other work.

the main problem is the floor I would remove the white tiles and use the same floor in the entire space

I love it! I think you should treat this space like the industrial loft space it is. Embrace the brick and the warmth, and find eclectic furnishings to match the scale. For inspiration, go check out Timothy Oulton's web site. His style is very much British industrial with an ultra-glam twist, as though an English gentlemen's club was relocated to downtown Manhattan. Alternatively, a Restoration Hardware look would also work nicely. Here are a few more inspiration photos for your reference:

I'm intrigued!

I'd want to focus on looking outward, through the arches, the atrium and to the landscape beyond.

Is there enough wall space on the brick walls between the arches for your pull- down movie screen? Could you position your seating to take advantage of both the outdoor view and the screen?

The contrast of the ceiling distracts from your brick because of the competing pattern of the arrangement of the beams. Is it in the budget to paint the ceiling a less contrasting color? I know it may seem like it would darken the room, but a softer neutral, but not dark, will help the room feel less cavernous. At first I was going to suggest painting the beams to match the ceiling, but when I look at your stairs and woodwork, then there may not be a clear "division" for doing so. I can't tell.

I'd love to see photos of your atrium. I'd want to make it inviting and comfortable. Greenery, seating, softness, etc.

Is there a history or an architect attributed to this house? Is that white floor tile original or added? The wood floor color makes it look like replacement, too.

You'll want lots of lamps!

What are the dimensions of the wood floor area? Was it originally a combined dining and living?

I see so many things that could be done, depending on your needs/wants and budget. Don't rush it.

I don't know if this is feasible but if you could switch out the can lights to "directional" lights to give a wash of light on your walls, it could really brighten up your space while featuring the brick.

This is a room I have always loved. Perhaps you can get some ideas? I love how the ceiling works with the brick.

I am in LOVE with your home. It is unique, has texture and is very warm and inviting!

I love your living room!

What a stunning space! A decorators dream space! If sky was the limit, I'd add in a nice chunky reclaimed wood mantle with some layered colorful artwork leaned against it, that would really pop against the backdrop of the brick. You mentioned a projection screen, what wall is that mounted to?

If you want a TV in that space, place it eye level, to the left of the firebox. The furniture there is not really working for me, but it can work if you want to keep it. I'd place your rug under the main seating area, I think the one you have there now is too small. My choice would be to eliminate the furniture you have now, and replace it with a camel colored leather sofa/love seat and a low profile, plush velvet club chair or recliner. Sofa would be facing TV/fireplace wall straight on, with sofa table behind it, with lamps, and decorative objects. It will help separate & define the living room from dining space. I'd angle the recliner out from the arched opening and the love seat opposite the recliner. End tables with lamps is a must. Next, add a vintage trunk style coffee table, with some books and fresh flowers to breath in some color and softness. Is that a doorway or opening in the brick to the right of the fireplace?