Consider a handmade, artisanal tile in a beautiful shape with a character filled glaze if it fits in your budget. If it doesn’t, think about a textured tile in a neutral that harmonizes with your countertops. This is Fireclay Tile in Frost in a Paseo shape.

You don't have a good stopping point for the window wall on the right side.

You will need to make sure the tile you pick has a matching pencil liner (quarter round), OR use Schluter trim.

You also need to make sure the cabinet on the left has enough clearance to open fully, once you add the thickness of the thin-set mortar and tile.

It is really beautiful as is. Are you sure it’s needed?

I also like it as is but I can see where you are coming from. How about a Roman shade? It can still be nuetral, a white on beige but with texture.

I get that you want something else decorative in here but I don't think tile is it. It will take away from the simplicity of your marble (?) backsplash and make that seem less of a correct choice. If feels like you have created a slightly British English vibe kitchen and now want to go American tile obsession on it.

Find two simple paintings to hang vertically to the right of your windows. Frame them the color of your island or chairs. Or hang a sconce. Your shelves look great as they are. Though I'd be slightly tempted to add antiqued mirror glass on the backs so a tiny bit of light reflects in slivers between all the objects.

if the window wall is the focus wall [ does the traffic flow create that visual line] then I would go ahead w some personality to a tile pick there. the kitchen is large enough to handle something...but what is your preference for style/color/ etc? behind the open shelves is quite a small area....work on the window wall first.

I find a color that you want to intruduce in textiles and art, and do the wall for the bar in that. handmade. Intentional - a focus area.

This may be an opportunity to add a little color to the space…the wall over the “bar?” … as well as the wall behind the sink

I agree a wall color might be the perfect answer to those 2 spaces and honestly I would get tired of a fancy tile very quickly in what appears to nice a nice simple well designed kitchen . Paint is cheap and easily changed tile not so much Maybe a piece of art even to the right of the window also easily changed

No, to the tiles. Instead, I suggest installing a fabric soft Roman shade above the window (outside mount). The shade doesn’t even need to be functional; its primary purpose would be to add warmth and texture to the kitchen without overwhelming its clean, modern aesthetic (your kitchen is gorgeous).
If you align the top of the shade with the opening to the right of the kitchen (the slightly taller doorway or pass-through area), it will elevate the height of the window and create visual symmetry across that wall by connecting the window and the opening. The shade could be a beautiful soft floral or print, or consider something in neutral linens or a patterned weave… maybe opt for light beige, greige, or a subtle strip to complement the cabinetry and gold fixtures. And then if you feel like something more is still needed, a beautiful piece of artwork to the right of the window is a nice idea.

@laswift would you do one large roman shade or 3 separate ones?

One large soft Roman shade.

And then I hope it’s obvious in my first comment that “a subtle strip” was meant to be “a subtle STRIPE”

Thank you! I will try to find a nice roman shade

No tile. Your space is beautiful as-is, doesn't need additional adornment. Do you need a window covering? If not, I wouldn't even put in a Roman shade or similar -- let the view to the outside be the focus. You could put some colorful doo-dads on the counter or bring in more wood with countertop accessories.