A reeeeeeaaaally tall and narrow plant in the corner? And/or art below the upper window? A rustic wood mantel or some kind of thick shelf that stretches the width of that wall, with baskets or something on the mantel/shelf?

Consider:

adding Tiffany style stained glass panel in the upper window

https://www.google.com/search?q=stained+glass+window+panels&tbm=isch&ved=2ahUKEwinxbDik9XoAhVEFVMKHRWiBkAQ2-cCegQIABAA&oq=stained+glass+window+panels&gs_lcp=CgNpbWcQDDICCAAyBggAEAcQHjIGCAAQBxAeMgYIABAFEB4yBggAEAUQHjIGCAAQBRAeMgYIABAFEB4yBggAEAUQHjIGCAAQBRAeMgYIABAFEB46CAgAEAcQBRAeUPieAlj9pAJgzbkCaABwAHgAgAF2iAHWBJIBAzYuMZgBAKABAaoBC2d3cy13aXotaW1n&sclient=img&ei=JNaLXqejFcSqzAKVxJqABA&bih=654&biw=1366&client=firefox-b-1-d

or art on the wall between the upper window and the door/window below

birds flying

https://www.google.com/search?q=Pressed+metal+wall+art+birds&client=firefox-b-1-d&source=lnms&tbm=isch&sa=X&ved=2ahUKEwiViq-3ktXoAhWjV98KHZfpAFUQ_AUoAnoECA0QBA&biw=1366&bih=654 

or art reflecting an interest or hobby

https://www.overstock.com/Home-Garden/Accent-Pieces/39/subcat.html?featuredproduct=22343153&featuredoption=37194177&kid=9553000357392&track=pspla&ci_src=17588969&ci_sku=27985161-000-000&cnc=US&cid=248963&type=pla&targetid=pla-411193465123&gclid=EAIaIQobChMIraHOkZPV6AIVrgOzAB3hrgHvEAQYASABEgJHjPD_BwE

or favorite destination

https://www.touchofclass.com/evening-sunset-wall-sculpt/p/Y362-001/?code=YMF03&color=&size=&tid=YMFPLA&gclid=EAIaIQobChMIjofFu5PV6AIVEZ-fCh2I-A96EAQYByABEgKI5_D_BwE

These are great ideas! I never thought to add art between the space. Thanks.

It is tempting to want to do something with blank spaces like that one. I think it's probably best to not add decorations there. Jinx explained the reasoning perfectly. Such talented people here.

I wouldn't add anything there either. You want your eyes down, not up, which feels unnatural. Also, do you need blinds on the top window? I would be inclined to remove them completely so it's always a light filled space. It's hard to give ideas beyond that without more context to the surrounding spaces.

Decorate where the people live; below the door and window frames - maybe 9 feet up. If that is done right, eyes should stay at that level. We need to see the entire area. What's behind the camera? What's the floor like? What's that on the right wall?

@Jilly @decoenthusiaste this is the other wall with the fireplace where the camera.

Should there be a window treatment on the window next to the door?

With the door and all the switches/outlets surrounding the window and the fireplace so close to where drapes should hang, I would forget about drapes. You can't hang them properly and they'll always be catching in the door (or maybe even catching fire.) My friend had a house fire this week! Try Fabric Roman shades and repeat them on the top window too.

Yet another reason not to build homes with two story foyers & entryways. I agree less is more. I'd eliminate the blinds on the top window. How do you even manage the controls for opening or closing them & the hanging cords add to the busy look. I like the idea of a roman shade on both the door & window next to it. The thing about roman shades is that they look better when they are rolled up or partially up. Rolled completely down, they can often look like a sheet covering the window. Another issue, if this is your front entrance, you might want the shades always down for privacy or light control. I suggest either roman shades that have some texture so they don't look flat when down OR a honeycomb shade that allows for top down/bottom up. Get rid of all those small items on the fireplace mantle. You will need something much grander there than that small mirror. I suggest colorful art.

Thanks. I think I can certainly remove the shades on the top window for added light and visual appeal. I also like the idea of roman shades on the lower window.

Is there a light fixture up there? Can we see the other side of the room? To the right of the photo and directly behind.