NONE of the above, and no picture molding. Just because a builder slapped it up in the dining room, does not dictate it in this room, especially with a "shelf" which is for what? Paint all four walls, and hang ART.The clean lined built in cabinets also do not suggest the need.

Your window style, suggests no such thing and it looks contrived to attempt it. Sorry...........NO. You're not living in a 1920 Georgian Colonial : )

Agree - I don’t think it will add much, the walls are smaller and a bit choppier and it just doesn’t work, which is why i think you’re struggling with how to do it

love the moody idea - add lots of texture + great art and you’re set

If you are set on applying, tape out a few options to get a better feel.

Just wanting to complement the DR wouldn’t be my basis to add, as it’s a small room with short/broken up walls. What are your plans for the wall between the bookcases other than molding?

Maybe create interest in other ways, ie: painting the ceiling the same as walls and using impactful decor. There‘s lots of on line inspiration, if looking for ideas.

Maureen - see that 1st pic is a smaller room and has picture molding between the shelves with artwork which is exactly what I'm going for and like the look of.

I see no need for the molding in the office you have lots of stuff that already breaks up the walls just the dark paint and some art and do not forget good lighting .

Maybe just add there and reasses room’s decision.