Our living room is fairly dark after adding on an addition to the back of the house. The dimensions are 13x23.

My problem right now is the corner of our living room where the window is. We're having a neighborhood party next month and I'm looking to adjust things in that spot - unfortunately, a big redecorating project isn't possible. We have an antique desk there which I've had a really hard time placing. There is no other place in the living room where it works (or for that matter in the house.) I would like to try to use it, but it has been hard. I'm looking for suggestions on making that corner of the room more attractive.

I know that we need to hang art that space.
I plan on buying a different floor lamp (or table lamp for the desk?) ... maybe a tripod type lamp that will give light to the room?
Not sure what to do about the chair.
I know that the mantel art is probably too small for the mantel.
I have a cat, so putting a tree or a large plant isn't possible. I could hang a plant though.
I have considered putting a very large framed picture next to the desk if the desk is facing the room.

I'll attach a bunch of photos with different variations. The leather chair that I put in front of the desk needs to be reupholstered in a different color. It doesn't have to go there. Ideally, I would buy a different chair and have sort of a reading corner, but I don't know exactly how it would look best.

Note that the window is quite low to the ground, so putting a table in front of it would be hard.

Thanks in advance! I'll be on and off the computer over the next few days but will check in periodically.
ACA

Here is some other information:

We have a seating area with a couch and two Bertoia chairs facing the mantel. The couch and chairs arrangement works as they are. NB: Facing the couch to the window does not work - I've tried it. (We do this during Christmas when we have a tree at the window, but the couch is a little too big to face sideways.) I love the color of the couch (kind of a wine color) which we recently reupholstered. Not totally happy with our reupholster of the Bertoia's (in gold), but we can't change that. (I'll post a picture in the next post.)

On one wall, we have a credenza and large matted Picasso lithograph. I'm happy with that wall because people see it as they enter our front door.

We painted last year an artistic taupe -- it comes out a little pink in the photos but isn't as pink in real life. I'm not thrilled with the paint color, but I can't change that right now. When we repaint, I will probably want to go a little darker and not pink - maybe more muddy?