I would buy roll(s) of grass cloth wallpaper and make DIY removable inserts to go in the compartments. Not sure why someone would say it shouldn't be done?

I really like the look as is -- has a midcetury feel, a little like a bookcase room divider. I fear if you really get something decorative in there, it will just compete with the actual books and decor.

To be honest, I think what you really need is decoration on the wall behind the sofa. This might make you scream, but I would go for something rather bold and graphic, and then paint behind the bookcases a color from the wall paper. And I'd put a substantial floor lamp between the end of the sofa and the chairs, and give the chairs some modern snack tables

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What a great idea, inserts! Trying to wallpaper inside those dividers with grasscloth or anything would be a lot of work, but inserts are a great idea and would be much easier to do. If you didn't like them, you just switch them out to another design idea (painted inserts rather than wallpaper, different wallpaper, etc.) or toss them.

I agree with mytwocents, though. Make the blank wall more interesting. Paint it as an accent wall or wallpaper it. Would be much easier to do or find a picture to stick there.

Consider fake, peelable grasscloth; much easier to apply and will save a ton of money. There are repetitions of space sizes, so might only need a few templates and lay on top of wallpaper to cut or paper the templates. You could also easily paint and if you didn’t like the look after a few are done, easy to paint over.

Whatever you decide to do, I’d pull the look together with large art and cushions.

I like them as they are this is a MCM type decor and the only thing I might change is less stuff on the shelves but I do agree you need some tables and lamps overhead lighting is not ideal by itself A nice arc lamp would be great centered over the Noguchi coffee table you could do the arc from between the chairs it will aslo give you a bit of atable for a drink

Thank you all for your suggestions! Regarding it working well as is - thats helpful to hear. Perhaps what’s been bothering me are the things in the builtin. I’ll look into reducing things there.

And then the blank wall - yes, I’ve been trying to find something for that wall just thought I would nail down the builtins first.

Curious, if I still want to wallpaper (something simple) or paint the backs, how light or dark do you think I should go? Originally I wanted to do something medium toned just to reduce contrast and warm it up. Nervous about going to dark because it could make the builtin have too much weight in the room. Thoughts?

I like the advice from @mytwo cents - get the art first and then work from there. i love wallpaper on the backs of builtins but I think yours look great and seem fitting with the room. Agree that a terrific floor lamp would be a good addition -

I would paint the backs of the built in SW Naval and use the grass cloth or wall paper on the flat wall behind the sofa.

I would also swap the chaise to the other side of the sofa near the built ins and the 2 chairs on the inside of the room ON the rug facing the built ins.

It's not your bookcase that needs attention..............it's the rest of the room

• I'd select a large piece of art for the blank wall
• Change out the pillows on the sectional.
• The coffee table seems grossly undersized. You have to take a bus to reach it from any of the seating
• I might consider painting the wall that houses the FP and TV.

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I would buy roll(s) of grass cloth wallpaper and make DIY removable inserts to go in the compartments. Not sure why someone would say it shouldn't be done?

I was going to say something similar. I'd buy thin, flat styrofoam (or cardboard?) and cut it into shapes to fit into the "boxes". This would be work, but you'd only have to do it once. Then cover them with fabric /tape the fabric on the back side. I say fabric instead of wallpaper because I think it'd be easier to work with /more forgiving.

If you want to change your color scheme, it'd be easy to pull out the styrofoam pieces and cover them with new fabric.

Thank you all. Will definitely put my attention on the wall. Very helpful to see that mock-up BeverlyFLADeziner - gives a better sense for what art could work. Any other advice for what to look for when choosing large size art work for that wall? Anything I should avoid?

Good advice here so far. If you do do anything with the backs I would pick a dark color like your chairs and just paint the backs.

GreatBigCanvas.com could be a source for art. First decide on the best size for the wall so you know what you are looking for. Art could be composed of multiple pieces or elements