I would install a grasscloth wallpaper in a soft gray with violet to repeat the couch colors or similar tones to the wall color. It will add needed texture to the room and really accentuate the architectural features of the bookshelf. Also, it will elevate your decor on the shelves. plus, if you can find a darker violet bauble/sculpture to pop in there that would pull it all together.

Thanks so much! The sofa is actually grey

May help, love the back wall of cabinet painted grey. You look like you have some things to put there, add some white accents

Yes! I love the grey on back.. Thank You!

Could we see the whole space and please get rid of 1/2 those pillows on the sofa. IMO before doing any decor on those shelves really think about what you have that is worth displaying , not just a bunch of stuff to fill them. I look at the examples above and all I see is a bunch of things really not that special and the amount of dusting to keep it perfect. I do however agree a dark background .BTW the vase on the coffee table is way too tall.