I don't recommend wallpapering a stairwell in general and a painted wall with art seems more in keeping with your style. You say you don't want gray anymore, but it looks like you have gray furniture in the living room. Are you planning on repainting the whole area the same color, or doing the stairwell a coordinating color? Can you post pictures of the living room? Regardless of what you're planning, it needs to coordinate with that room.

I am painting the entire floor and getting new furniture redoing it all !

Wall color can come after you select the new furniture.

love the large piece of art, if you are keeping it, I would not paper the stairway.

freshening up the space with SW Alabaster would compliment the art.

Stark white trim is too much... paint the trim and walls the same color.

I agree with Lyn Nielson. I’d repaint to lighten everything and then reaccess the furniture.

Choose the paint color last--after you have gotten the furniture, rugs, etc.

Also, I would wallpaper the wall of the stairway. It would really elevate the design of your space. Since you are getting everything new, it is nice to be able to start from scratch. Good luck on your project.