Very nice indeed! & if you plan on spending much time in the chair, I would position it to enjoy the nice view, just like the sofa. It is so neutral, I think just about anything will coordinate w/ it. Just sayin'...

Long console on the TV wall and TV siting on console. Lose the shutter as they are taking up real estate and breaking up the room; replace with cell shades or blinds, add stationary curtain panels. Center the sofa on the long wall and center the art work about 5 inches bottom of art from top of sofa back. Place your two chairs on either side of sofa on an angle so you can see tv from all seating areas. Buy two small cubes to act as ottoman/cocktail table area for extra seating and stuff. Add matching end tables and matching big lamps on each end of sofa and large piece of art over sofa; think Pier !, TJMaxx, etc. Post pictures. paint the room all one color for unity and to make it appear bigger. Here are some ideas of smaller compact sofas. And they seem to have room to add your two small chairs for extra seating.

Once you have furniture in your space the chair rail will not be noticed on that side. It will not be the focal point. Your furnishings and artwork will be what people will see. Also, spaces that are completely balanced are not nearly as interesting as having a little asymmetry here and there imo.

I would use the den as TV area with TV between the built-in bookcases. Then do a back-to-back arrangement with two sofas (they don't have to match) and a rolling sofa table between them. The one in the den would be the guest bed. When you have guests, simply roll the sofa table under a window and close the sliding door. As an office, place a desk facing the window if you need good light for online conferences, or put it on the wall if you don't do that. A rolling desk chair can move out of the way for the sofa to be opened. In the living room side, use a round dining table in the corner right of the fireplace. A coffee table 12-18" from the sofa and perhaps a pair of small scale upholstered armchairs in an "L" with the sofa, their backs to the window. Art, not TV, above the mantel.