Back up and take a new picture. This small spot does not exist all by itself. We need to see what else is around.

Here are some pics from further back. It is a space between the living room and dining room. Classic trilevel layout

And even farther back…

Visually, it is not one wall. The support beam (maybe because there was a wall removed?) makes one side dining room and the other side living room. Buy a similar piece of art as the dining room and hang on either side of the entertainment center. To fill the empty space left on dining wall, hang a mirror. Would hurt the paint the three pieces, either.

I wouldn’t add any art to wall because of the large art in dining room. But, what about a tall floor plant in a pretty pot with a color that goes with your decor - blue? The greenery would bring life to space and soften the separation between rooms. Looks like you get a nice amount of light so maybe a Fig or Ficus tree? I’d place it closer to LR side than the DR side,

I hadn’t even thought of a plant! Great idea

Looking at my photos I’m wondering whether my living room needs some side tables as well?

Well, - you do have a minimalist look as far as furniture goes. 😊 How do you use the LR space? Seating looks like an arrangement for conversation - TV watching not so much since no seating except the one chair facing TV, When sitting in LR, do you read, have a cup or glass you need to set down somewhere? A table between the 2 chairs would be good - the chairs would need to be closer together to have easy access to table between them, The coffee table could then be pulled a bit closer to sofa. Maybe a little bit of rearranging seating will be needed?

I love it! Any particular types of tables to search for? Material, shape, or size?

And to answer your question, yes the room is mostly sitting, although we do watch our fair share of tv

Because it’s one piece you’re thinking of adding, I would look for a round table styled same as coffee table. I searched Wayfair for ’round wood end table” and several came up that look a close match to your coffee table. Height of table should be close to height of top of arms on chairs. Since you do watch TV, & without knowing dimensions of room & sofa, have you ever tried the sofa facing TV? The 2 chairs could be facing window as sofa is now. or, have 1 chair each side?

I would turn the LR rug, face the sofa to the TV and put a chair on each side of the TV. Another possibility is to put the bookcases together on the right side of the TV and then a plant and floor lamp left of the TV

Once you bring in a few tables, add some lamps.