Rather than focus on the wall of windows you might first paint the walls a mid-tone or darker which will do wonders at warming up the room. You may not then need to dress the windows at all. You have very valid reasons for leaving them uncovered. Window coverings for that expanse of windows will be very costly and there are many other ways of warming up the room. If you are interested in having plants to soften the space you might consider a couple of Dieffenbachia as they are fairly inexpensive when small and grow quite quickly. Of course there are warnings about the toxicity but I've never had kids or pets eat them and I have read that warning is over-rated. I've had one grow to over 8' tall and seen them much taller than that. They actually do better in lower light situations and mine did well in a north-east window. Whatever plant you choose you could put it on a pedestal when small for greater impact. I'm not a fan of accent walls so wouldn't advise painting the fireplace wall a different color. Too often accent walls don't work as intended for interest and I think there is enough going on in this large room so that keeping all walls the same color would be best.

Part of the reason the area looks bare and rather cold is because it doesn't have a rug, but it also definitely needs art on the walls. It's a large enough area that a gallery wall would look good there. Look for "gallery wall" on Google or Pinterest for lots of ideas for inspiration.

You said that there is a closet directly below this opening? Do you mean on a different level? What is behind that 3.5 feet of wall that is directly below the opening? Is that empty space behind that wall? If so, why could you not knock out the wall and make a full closet out of it? It can't be a load bearing wall. Instead of installing complicated pull out anything, you might have empty and unused space behind that wall that you can open up and have easy use of. I am having a hard time envisioning this space and it's placement. It looks like there is a staircase to the side. So this is built like a large rectangular box that projects from the lower level up into the upper level with a full closet on the lower level and this truncated closet on the upper level? Essentially, it is two closets stacked on top on one another with the upper of them being partly closed off across the front to create this deep, short space? Do you have any idea what it was used for or built for in the first place? Do I see an electrical outlet in there? My daughter's house has something similar to this in one wall of one bedroom. It seems that it was built to hold an old fashioned TV. Did this maybe hold some old fashioned stereo equipment? If you don't want to open it up ,just put some sliding doors on it and accept it's limitations. But, I think that you have a closet space that is half way closed off that you could open up to to a full closet. A full closet area right there would be as useful and accessible as any other full closet. Leaving it like that is wasted space for you since you are not filing it with electronic equipment. Not only is the space wasted, but it is presenting to you as a problem that you are trying to live around. Once you have the space fully opened up, there are any number of things that you could do with it.....use it as a closet, put a desk of some kind in there, fill it with built in bookshelves............... Change it to something that works and that uses the full space. Instead of altering your life around it's inconvenience ...... alter the space instead. You can spend a lot of time, money, and energy trying to apply all manner of convoluted shelving and still be left with an awkward situation.

Hi @Maegan Coolbaugh. Sorry for the delay. I've generated a 3D build of your room. Placed your tv on the opposite wall with a panel behind it. A couch facing the tv and another one next to it forming an L shape.Two swivel chairs that can easily be rotated in any direction or moved away when not in use. Completed the seating arrangement by adding a rug. It is important to pull up the area together which can be aesthetically achieved by adding a rug that goes well with the items placed on it. If you are planning to take down the short wall near the stairs, great! Else you can simply place a see through bookshelf which can act as a partition to diving a small space dedicated to reading/work or serve as a private conversation spot. Placed dining near the window. It could also float a little more towards the kitchen. I placed a crockery unit to provide for some storage. You can add more storage based on your requirements. Let me know if this was useful or if you would want me to work on more layout for you.