I'm not an expert, but I think seeing a sketch of this room's floor plan w/ dimensions would be helpful.

What is your focal point - the window or the fireplace? It can also be a favorite piece of wall decor. You can have a variety of seating combinations. I like one couch and several upholstered chairs. Get some poofs and ottomans for extra seating. You can also put trays on the ottomans for drinks and tv remote controls. Make sure the arms are narrow, so they don't take up a lot of room. Measure twice, buy once! You have an off-white everything background like in my living room, so you can pretty much have any colors you like. I only buy one couch every 20 years, so I get a very classic color and excellent quality. My sister gets a new couch every few years, so she gets one that's more trendy, and less expensive. Depends on what you want to do. What's your style? Mine is eclectic, which means a combination of different styles. To see different styles, put in top search box - modern, traditional, transitional, country, rustic, etc. Also consider storage. If you are a neat freak, open shelving is ok. If not, cover the clutter up with doors! In my opinion, one can never have enough storage. That being said, don't make the mistake that I make which is wasting storage space on stuff you don't use or won't look at for years! Get your basic plan before starting.

I'm looking into whether an existing vertical blinds track can be re-purposed, but for the wider panels...

Here is a pic of the room around the corner

AE - post a photo showing living room's opposite end.

Here is what it looks like now. I just think it looks too dark. Maybe a simple change with the pillows and curtains would work?

Well, that quickly went from clean slate to furnished. I agree it looks dark. What type of window treatment do you need in terms of privacy and sun control? What's under the TV? I like the idea of mirrors in a room to bounce light around but I don't think the small mirrors are working. I'd consider large colourful art on that wall instead of the black piece.

It's very monochromatic - even your artwork has similar colors. It's not a bad thing at all, but I personally like pops of color. (I know it's an overused phrase here, but that's my preference). I like my big items to be neutral because I change my mind an accent colors every couple of years.New pillows and curtains would go a long way to brighten up the space.

I also think you have a too few many things in the room. I would remove the trunk looking piece next to the sofa table behind the couch. I think the LOVE picture is too big for the space - I would move the two small pictures next to the tv in that space and leave only the tv on that wall. The grey chair to the left of the fireplace, while I like it, seems unnecessary. I would probably leave that whole area empty to use as a walkway. You also do not need the floor lamp to the left of the tv stand.

Many photos don't show what a place looks like in person... I like your variety, interesting tree-ring slices.... if I may say that at quick glance there are 2 too many: mirror over the chair, and LOVE cause it's squished.

Curtains are dark - change them? Is it possible for 2 units by tv to share the same stain? chalk paint might do it. The large textured screen [and I like that it's large, and it's 'thin' too] -- but it might seem better if DIY you wove macrame-type material through all or part of it. The dark frame could remain.

Easier if large rectangle were sprayed a medium neutral. Are dining chairs of metal? DIY and course idk if that's an idea - a metal might look better woven through, and it could be asymmetrically arranged [like art is].