Color is such a personal choice. Are you looking for a bright POP of color, or something subdued?

I have 2 red cube ottomans that I might bring up and see how they work and if not, reupholster. I like the idea of a bright POP of color but I don't want something trendy. I want both of these pieces to work in 5 years time. Something timeless ...

With that neutral background, just about every color is possible. I see a bit of rusty red and yellow in your accents and they both look nice. I also really like the green in the picture on the bottom shelf over by the fireplace. My least favorite is the light blue on the sofa pillow. Nice job renovating. Do you have room for a narrow sofa table on the wood floor behind the sectional?

I see your blue pillow. Blue is supposed to be a big colour choice for the next several years.

Go red!

@ann, no unfortunately I can't move the sectional forward due to spacing and the wood floor behind is our main hallway and it's a raised floor.

This all depends on the feeling you want. If you want it to feel tranquil pick pale blues and/or soft yellows. If you want it to feel smart and engaging do the chair in an orange stripe or chevron. If you want it to feel cozy, stick to neutrals like chocolate but opt for textured fabrics. You could pop bright orange or bright yellow if you want it to feel modern, both would look great with the tonal grays of the walls and curtains. I think you should paint the area behind the shelves of your built ins because it would break up the white expanse. The only colors I think you should stay away from are red and green. Green because with the slate floor would feel too much like camouflage and red because it with the black floor reads 80's or Chinese restaurant to me.

The room is restless created by too many small items or by red, pale blue, green. Accent pieces should be bold and add pop to the room.

Colors you love will be timeless. Why worry about what the rest of the world is doing? The rest of the world doesn't live at YOUR house. Just about anything will work, maybe you need to widen your pallet to two accents, like brick red and moss green. Browse. See what grabs your attention, what you're drawn to. My favorite color is apple green, and for me the accent color is burnt orange. Not everyone can live with the visual impact, but it's what I love. If you keep your big pieces neutral, changing your accent every couple years is no sweat, and you'll never get bored!
After looking at your room again my other suggestion would be to choose a large piece of artwork for that big blank wall, and pull your accent colors from that!

I agree on the glass coffee. Put the ottomans under the window to be pulled up as additional seating. I'd suggest you find a larger and patterned area rug from which to pull an accent color, and put the front half of the sofas on it. Keep the accent color interesting but subtle and paint it on the backs of the built-in's shelves and behind the TV. Then pop in a few pillows and a throw in the same color. Look for a large piece of art for the wall to the right, and lower the one by the curtain so the center of it is 60" off the floor. Replace the ceiling fixture with a with a strip of can spots to focus on the shelves and their decor.

The blank wall to the right is for a collage of family pictures, just haven't had a chance to hang them. I do love the idea of painting out the back of the built-ins and seriously thought of this during renos but could not and still can't convince the Husband. As for the lighting, yes that's on my never-ending list. But what does 'strip of can spots mean?" Any ideas for rugs?

I think that you definately need some pattern as well as some color..perhaps something like these items might work.....

Sherwin Williams has a website where you upload a picture of the room. You can tap on hundreds of colors and it turns the walls that color and you can see and most importantly, you can feel the room. Color choice should always be the feeling you get not what is trendy at the time.

Yes to glass coffee table, and IMO the chair could in itself be not just a pattern or different colour but a piece of art. Something easy to move, comfortable to sit in and not take up much visual space.

Check the big box hardware store for a strip fixture that replaces your present light fixture. It has strips to right and left that attach to ceiling and have capability to insert can spotlights that can be slid along the "track" and positioned where you want them to hi-lite.