I thnk your gray walls are working against what you should do here. It needs a lighter hand overall. Its hard to tell how much daylight or natural light you have to work with. If you can at least temporarily open the blinds and push curtains back to see what effect you have as a starting position. It looks like a good space but the feel is not helping and this is a light issue. If the dark cabinets stay I'd do a white basic ceramic subway tile. You want a light spare clean approach...not mosaics. If you can pick a nice light bone off white I'd start eliminating the gray walls....this would be a great benefit . Deal with lighting then. I see very few table or floor lamps . Then on to wall decor. I see a couple club chairs and a dark dining set so its hard to comment ..Cant really tell your aesthetic taste. Walls can take artwork of course...but bookcases can be built in...other things are options .

What about some rugs (I know this is not what you asked)? Maybe you live in a hot climate and don't prefer rugs, but my feet are hurting looking at all that tile! At present, the drapes are the only things bringing any colors in.

Agree with above comment to look for a light color or white tile to match the countertops and add some light to the kitchen with all those dark cabinets. It doesn't have to be "basic" if you're feeling you want something special, but I think it should be all light in color.

Cheap art is nicely framed photos you took yourself. Keep the frames consistent. It often looks classier and more interesting than far more expensive, purchased art.

Thank you all so much for your comments, for someone who knows nothing about deco this is really helpful