I'd choose similar art for each side. Something like below:

Paddington Terrace · Еще

Your slate is earthy with olive undertones .. pick your wall gray carefully to work with the stone, not with your upholstery .. . better to go more neutral . .. not matching but coordinating art makes sense . cabinets may want to help you bridge the gray challenge .. .

Can you photo the whole room w/ each wall so we can give you more informed advice?

I would put two matching silver leaf mirrors over each one and then accessorize them differently. The mirrors would reflect light from the windows and make it brighter in that room.

when you say "the room will be painted gray" do you mean the tv wall will change too? is it dark grey / pale grey / medium?

I do like the tv being on a very dark wall (like mine) as once your tv is switched off, tv will hardly be noticeable on wall. So your focus point can be on more interesting things on the wall.

However I do find these 2 white beautiful pieces a little too bright against the wall, it bothers me a little. But they are stunning...

However if you do decide to keep them there, there are options such as round mirrors (to add some circular shapes in the room), vases with faux flowers, or a large frame "plonked" on each. Avoid the "family framed photos on each" might be cute to some, but for me it's not stylish, my in-laws just overdosed on it so I am a little traumatised by it.:)

I also suggest an area rug:

Flat Weave Stripe Pattern Blue Wool Handmade Rug - CC03, 4x6 · Еще

That was too small. How about this?

Modern Geometric Pattern Gray /Black Wool/Silk Tufted Rug - BL89, 9.6x13.6 · Еще

Surya Athena Transitional Hand-Tufted Wool Rug · Еще