oversize statement lighting on either side of the fireplace would look good. the current lights just seem too small

If you hang art on the sides, use proper art lighting if these lights are not for that purpose.
The upper part of the chimney area needs to contrast more with the walls.

Put the tv anywhere but above the mantel. It is best at eye-level to a seated adult.

That is a beautiful fireplace! I think they hardest part about decorating any empty space is picking a focal point. Too much going on and the eye starts to wander. Since you have such a beautiful tall fireplace, I would make that the focal point by painting it a dark seat to match the gray paint you currently have framing the fireplace. I would then go the built in route- white ones on either side of the fireplace. You could do tall or low and wide, because your fireplace is so tall I don’t think either would distract from the focal point. The lights may look small now but I think that’s bc everything else is so large and they may fit better once you add in larger pieces. I wouldn’t add anything too large to either side of fireplace. If it’s art or mirrors I would keep it definitely smaller than the fireplace, since that is part of the focal point and should be one of the largest pieces. I would maybe raise the TV up a bit but I prefer it over the mantle. It doesn’t need to be eye level.

.

@deanna thank you for your input, we were actually talking about painting the rest of the fireplace dark yesterday and your mark up really helps visualize!

So you think the built ins should be the same colour as the wall? That may help because we’ve added so much stuff and it looks too busy.

We took everything back lol

Another thought: since your lights are already hardwired into the wall, open shelving would be a better option than a tall built in. If you put in tall built ins now they would stick out past the lights. Most built ins have the lights attached directly to them (see last pic). The first two pictures attached illustrate open and closed shelving concepts that is personally think would look fantastic in your home. If you went with the closed door built in option (middle pic) then I think a smaller mirror or the print you had picked out would be fine. The print/ mirror plus the open shelving units in your pictures is what is making it look visually cluttered. Whatever you do though- it’s going to look great!