What about roman shades? To tie the fireplace and the built-in together, maybe put a rich dark brown fabric swag on the mantel and have it hang down just over the top row of stone? Then so you don't have fabric overload, switch out the tapestry for a mirror or a painting?

I would not recommend hanging fabric near a fire. The dark wood built-ins and fireplace are not aesthetically ideal in terms of design even if the built-ins were the same color as the fireplace. However, assuming you plan to keep the built-ins, fireplace, and yellow walls, I would suggest painting the built-ins white since the shelving unit on the adjacent wall is white. If the built-ins are against the wall vs. inset into the wall, I would then continue the built-ins above the fireplace so the entire area looks more like one unit. (A new longer trim piece would have to be put across the top.) I would suggest painting the walls a light neutral from the fireplace stone. Given the limited amount of natural light, I would not suggest doing plantation shutters and would do Roman shades instead.

Don't paint your kitchen cabinets! That introduces a whole other issue into your kichen. It looks nice as is.

Yes, paint the built-in *and* your fireplace white. Get a white coffee table or paint it white as well.

Add light, or white window treatments. The white shutters may also work.

I suggest white cotton slip-covers for the furniture if you are keeping it. If you are open to it, a lighter floor or carpeting would be great. I think that's a big reason things don't feel united. It looks like a dark grey, but a majority of your furniture is brown.

Yellow and white is a cheery combination when done well and your particular shade of yellow is one of the few I like, lol. So if you like the yellow, keep it. It looks great with white.

Tweak a few things on the bookshelves (edit/declutter/rotate items) and those few changes will help a lot. It will look and feel brighter and more fresh.

That yellow also looks great with royal blue if you are looking for an accent colour.

Don't go crazy--a few tweaks and you are good to go. Your space will feel like new.

Cheers!

Thank you so much for your comments and advice! I think the picture is misleading. The carpet is blue berber, the couches are off white or natural linen, the walls are a light lemon yellow ... The house has a very open concept without clear borders between rooms in the main living space - the rest of the house interior is various shades of yellow/gold. The family room tv built in is actually recessed into the wall of the house - equivalent depth of the fireplace ... So it wouldn't be possible to continue it around
the fireplace. Also, it was kind of dark this morning in the room but during the day it's fairly light. I'd love to put wood beams in the ceiling but that's probably too big of a project.
I wonder if a large round mirror (instead of the tapestry) would help balance out the fireplace wall? Or if I should go for another rectangle but perhaps a bolder frame?

Also if I remove the light box in the kitchen ceiling - would you do 3 or 2 pendant lights or multiple recessed lights?

You could try different things to experiment, but the way that you have the tapestry, rectangular and makes the fireplace section the same height as the built-in, is pleasing to the eye. Just from this picture, the medieval feel of the tapestry and candles might not be a match with the style of the built-in, which appears more deco or craftsman, from this distance.

Lighting is also a matter of taste, but recessed lighting feels contemporary to me, and not as much personality as well-chosen co-ordinating pendants.