Woven roman shade on window in a light finish, creamy white.

New dining room table and chairs in something sleek and clean

This room has teal counter stools and a table and chairs that would look wonderful in your kitchen. I selected teal because it looks like you have that color in your light fixtures, but the most obvious color in your lights would be the best choice, whether it is green, red, purple then have a rug and art work done in a shade that is opposite that color on the color wheel.......The woven chairs blend nicely and soften things up. Note warm sisal run and warm art work to counter balance all the dark cool tones.

counter stools in black or cream

Maybe a pair of eterges on either corner of the eating area in Black or Deep plum and filled with serving dishes?

Oh I was wondering what type of backsplash is on the walls? It is very unusual?

An area rug under your table will also help with the 'echo'. Here are a few ideas for the walls- all at Wayfair - hard to tell your exact colors in the brick from your picture, but I attempted to compliment the brick colors in the art:

Framed posters and DIY art work can be fun!

I love diy art work! Thanks for the images.

Uttermost 06909 - Uttermost Time Zones Wall Clock

Some ideas, love the deer.

I like the starburst with the silverware.

I think the under counter lighting needs to be changed to something warmer in tone, it is making the brick clash with the cabinets and beautiful countertop

I would also faux finish your black outlet covers they are ruining the look of the bricks as well

Agree that there might be a lighting issue...your cabinets are coming across light green. Maybe from the amber pendants?

Do you have 2 user names??

Cover the whole wall in pennies with glue, should add nicely to the other textures, colors and lines in the room..the copper color will just be one mor interesting item in the space,use craft paste and slather it all over

The wall isn't the issue. Blank walls that just need art aren't a problem. The color clashes between the major elements is the problem. The backslash is the primary offender.

Here is a better photo of the counter area

Does the brick backsplash stay? It's really busy with the granite. I'd suggest small scale glass tiles in neutrals pulled from the colors in the granite. Also, try a strip of power outlets running parallel to the underside of the upper cabinets!
For your breakfast room wall, I'd like a large contemporary style print with a few bold colors. Nothing too fussy, it's going to make the area too busy!

Any art will do. It doesn't need to "match" the room. On the other hand, the backsplash DOES need to match. That burgundy and grey brick needs to go. It doesn't go with the golden and orange tones of everything else. It's a huge misstep in an otherwise lovely space. You might try just painting it out cream. The texture could work if the color wasn't so off.

I think you have some good suggestions here, but I would recommend something with a bit of color in it to add a bit of punch to a neutral room. I like old travel posters from the 1930s which are available online for not much, colorful plates from the thrift store, framed fabric as was suggested (try Spoonflower and Etsy) and shelving units with vases or pitchers on it. I would go big and dramatic if I could, or group like items.

I would also consider painting the wall a different color and something rather bold for an inexpensive way to add a bit of punch. The existing color is OK, but a bit on the drab side and fairly dark. I would pick something that would pick up colors from the adjoining rooms, or is a favorite for you. If you can't bear picking a color, perhaps just a lighter shade matched to go with the cabinets would work. Actually, multiple neutrals may seem like a safe choice but they are harder to get to work together than something with a color.

The right color and some related accessories could tie it all and the misc. neutrals together. It may take some experimentation to figure out what color that should be. Since the backsplash and counter are pretty busy, I think whatever you pick should be a quite strong in color to stand out. Anything too subtle will be lost, unless you hang it on a wall with some color.

So either go colorful with the artwork and accessories to contrast with what you have already, or go subtle with the artwork and accessories and colorful with the paint. Look at what you already have and pick a direction.

I really like the cabinets BTW.

The granite and cabinets are really nice and I like the texture the backsplash gives, but I would suggest painting it in a color that doesn't clash with the counter. It's hard to put art and color on the wall when the colors in the kitchen are so off. What is the flooring?