I thought I would include a few more pictures to better visualize the room.

I would use a solid color..maybe a texture, but a solid color. I also would do simple panels without the "doodad" on top. Maybe a dark cream shade, 4 panels. Add great pillows using colors (some solid & some stripe, etc.) on the sofa. Very large art on the walls.

Change out the light kit on the fan (if you are keeping it and not replacing it with a chandelier) with a bowl type light kit. I would also paint the newels & rail your trim color (white). Did you ever consider having someone trim out your windows and doors with real molding? It would really dress up and change the look of the area.

Thank you Barbara. Honest opinion, does the wall color look overpowering or is it because the walls are so bare?

The walls are fine...it is because they are bare and void of color. Think large colorful art. Be sure you don't just decorate the lower 1/3 of the wall..go up up up.

Wondering if a different rug would tie your furniture in better? The walls seem really blue in the photo and the furniture seems greenish grey..but that could be lighting and computers, etc..

Ideas

the rug seems a bit stark. maybe it could move to another room when you find a rug with more of the wall color and a dark background.
consider a large textile for the wall viewed from the stairs. look on etsy/fiber art wall hangings or etsy/art quilts. browse pinterest for ideas.
one large canvas would be better than smaller pix over mantle.
pretty house and the walls are fine. they just need dressing.

Love your space and the direction you are going. I can see either a desk/hutch/cabinet at the bottom of the stairs on the wall between the doorways. The one below is a desk and hutch combo. More throw pillows in brighter colors and patterns. An ottoman maybe in a rattan look for texture. You drapes have to make a wow statement, but I would avoid a pattern. Hang them as high as you can. A table between the chairs to give them more of a function, with a lamp. I agree with the chandelier look. And if not done already, a dimmer switch. I think some artwork with down lighting would be cool on the stair wall. I think your mantle needs beefing up- it seems small for the wall. After pics please!!! Can't wait to see the end results.

Thank you all for the suggestions. The sectional is gray and the 2 chairs are a dark brown leather. I really want the drapes to make a statement. The rug was a recent purchase so it will have to stay. The wall color is a stronger blue than I thought but I must make it work.

Does anyone know of a software that will let me see how drapes will look on my windows?

@kat010 ...I am sorry, I do not,,,but I think tying the cool/warm colors together with draperies would look good...do u have any ideas yet on fabrics?

Blues are tricky, but if you get the curtains and accessories right, it's a beautiful shade. I think, because the sofa looked brown to me before you said it was grey. One think that stands out when looking over the pictures is how bright white the trim work is. Since the blue has a muddy, versus a clear, undertone, it might look better with a creamier trim paint. Is the fireplace more of a cream? It seems to balance nicely with the blue and a version of it (maybe a bit whiter but with the same undertone) as the trim in this room might balance the blue better.

No decision on fabric yet. So many options it is a bit overwhelming. Yes, the fireplace is more of a cream color.

Big tall panels will look great. A solid or a pattern would look fine. Agree with Barbara on BIG art.