If you have Art in this room, I would choose colors and tones of the colors in the Art to liven up all the neutrals. Maybe .... coral, mid tone lavender/purple, muted lime green and some gold/yellow, or combo there of.

Another

Leaf tan, brown, orange, lime, yellow · More Info

Sorry but the blue walls and grey rug IMO don't work with your full selection of furnishings.

To tie the room together, on the single chairs I would add a rolled green/bluish grey pillow that will harmonize with rug, walls and chairs.

Green Art Silk 12"x18" Metallic Beaded Lumbar Pillow Cover, Green Center · More Info

On couch, elegant cream/green pillows and mix with a solid, see picture below. I think it's important not to add any other colors, but to create harmony by using subtle graphics and lovely fabrics with what you have already.

IK Ayaka Green Velvet on Linen Pillow With Down Fill · More Info

I have a feeling you have a second picture over the piano that matches the one above your couch and I think you would get a lot more impact above the couch if you used both there (and lower). Accessorize your coffee table for more interest like below.

Living Room · More Info