I like the Instagram picture. If you're going to go asymmetrical, it has to be way off center so it looks like a design feature, not an accident. I like the look of the stone (I'm assuming you plan to remove the small brick surround you have currently). I think going floor to ceiling would actually add some visual height to the room which would be nice. If you're unsure, you could try painting the wall (and the brick surround, if its definitely going away) to emulate where you want to put stone. It would help you get the feel for what it would look like. This would let you play with proportion as well, to figure out how wide you want to go. (I think i would go more narrow that it is tall. I like the proportions you mocked up in scrap wood.)

Agree with gracie01. Move TV to console on left of FP. Make sure the console is at least 2/3 the width of the space from the corner to the FP and center it in that space. Hard to tell but I think I would go with a much larger rug so the recliners are on it or pull the recliners in so the walkway is behind them

I think the contrast between the classic FP surround and the contemporary shelves on the right is more of an issue. I'm not a fan of big box store decor, so the items you are decorating with aren't to my taste, but what probably makes it "off" to you is the fact that the coffee table isn't lined up with the firebox opening and the sofa is partially in front of the opening. You might sense better balance if you flank the FP with the two chairs and place the sofa where you have the floor mirror, centering it and the coffee table with the firebox. If you remove the shelves, you could try the floor mirror on that wall instead. You don't have much walk space around the sofa right now. The chairs might do well on that side, leaving the step down entrance clear. I'd rather leave the space in front of the step clear of furniture.

You don't really need a coffee table, since you have the side tables. Just tuck a c table under the side of the couch where there is none. That should free up some space. Since you want to put a unit where the chairs are, the chairs will have to be relocated. Even with your two couches and chairs, you only have eight seats. Add more with poofs or ottomans. Relocate the two chairs in front of the fireplace (with their backs to the fireplace). Or as suggested, move the couch that's in front of the window to face the other couch. Then the chairs can go in front of the window. I agree with art going around the tv.