pic with window

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First - do you want to emphasize the window or make it go away?

My first thought would be to use panels, full wall height, on either side of the window and an arabesque patterned cream and dark camel ... go with a lot larger or a lot smaller on the fabric pattern compared to the carpet.

For inconspicuous ... a very low contrast arabesque in cream and pale camel, as a roman shade mounted inside the window.

Why do you need a treatment on the window? That might help with the decision process.

If it is for decoration, I would do a roman shade.

I don't "need" to put a window treatment on the window since our house sits back and is in a wooded area, but I think it would look nice.
Regarding your suggestions lazygardens, I didn't think I wanted to be so matchy matchy with the carpeting, that's why I thought perhaps a different pattern opposite of the rug or even a solid.

I do prefer a drape over a roman as I have a lot of romans throughout already.

If you want to just soften the area, I'd go with a solid fabric that is close to the wall color and hang simple panels on each side of the window.

Shutters is another option.

An inside mount white sheer panel over the bottom sash that stops at the sill.

You certainly could leave it bare, but if you want something, it's great because it doesn't have to function and provide privacy or light control. It just has to look nice.

So to just to soften the look, you could go with something like a fan shade in a white sheer...something like this, but without the flowers.
{{gwi:2137767}}

Or you could do a sheer with a bishop sleeve in the middle so it covers the top of the window and is drawn up in the center...like the top drape in this photo without the privacy sheer behind it...only I'd start at the top of the window, not part way up like they did.

{{gwi:2137768}}

[Traditional Powder Room[(https://www.houzz.com/photos/traditional-powder-room-ideas-phbr1-bp~t_713~s_2107) by Toronto Photographers Peter A. Sellar - Architectural Photographer

I think the only constraints you'd have are, you don't want to block too much light as you need it to see the stairs, and you don't want anything that hits the floor as it could be a trip hazard.

So you could do sill-length side panels, lambrequin, cornice, valance, shades like balloon, cloud, soft roman, etc. Lots of options.