I wouldn’t do sheers with an upholstered cornice and shades with fringe - too many contrasts. That is a bold pattern for the shades so I would do the cornice very simply, possibly just a contrasting welt cord in navy as it appears you have other blue in the room.

Thank you clt3... I said I'm NOT replacing the shades with fringe... all of that is gone... just new cornice boards and maybe some side curtains. I'll edit my original post to make that more clear. That fabric from the 90s is no more. The only navy currently in either room is in the rug in the dining room.

You will probably get some people on here to tell you that you should not do the cornice boxes. Not me. We have them over some windows in our kitchen and breakfast room because it seemed that there was just too much blank space above the windows. When we remodeled our kitchen over 13 years ago, our window treatment professional suggested a very bold pattern for the cornices, and we went with it as the fabric's colors and patterns tied the room together. I was always a little uncomfortable with it (our home is traditional, but it just seemed a bit too much). In 2020 we repainted, upgraded FR furniture, and re-did the cornices in a textured, light blue/green that blend into the wall color for a more modern look. We have no trim, just same fabric welting, and we do not have anything above the French doors, just the windows. It is a much fresher look. I would not do buttons, tufting, or contrasting welt. The textured fabric should be enough interest. Also, we kept our woven shades from the original remodel.

Thank you, @decorpatti. I appreciate your input (and pictures!) and that you took time to respond. I've definitely decided against tufting as I can see from the mock-up my upholsterer did for me that it would be a bit much.

I would say plain with welts but no buttons, no contrast, and if you are using one of the more open weaves consider using this unlined as a shee after talking to the fabricator to see if that would stretch too much or not. I grew up in a house that originally had some fairly heavy weave, unlined casement fabric as curtains and I thought it was a nice look

No cornice boards because they will visually lower the ceiling and height of the room.

Either Roman Shades or drapery panels.

Thank you, @palimpsest, for giving me something to think about re: the curtains. And I think you're right about no buttons. I'm not sure I like the 'almost tufted but not quite' look of just buttons on cornice boards.

I've been playing around a little... I couldn't find a textured fabric, but here are plain fabric cornice boards with welting... too plain? Just enough?

I am not a fan of buttons that don't look like they are actually doing anything even on furniture.

And another picture...

With welting...

With no welting...

Thank you @la_la Girl. I am looking for fabric that blends in with the paint... something beige with maybe a hint of gray in it to pick up my carpeting. After reading some comments here, I decided no buttons, but had been thinking about welting. Thanks for you input on that. The look with curtains above is close to what I want.

I would do welting in the same fabric as the cornice. For me, welting makes it a bit more "high end" and more finished than a plain seam.

I prefer welting too using the same fabric.

It’s probably too late, but a slight curve to the cornice softens the look.

Excuse the Christmas...but if you go with plain wood it will take you longer into the future w/o looking dated.

Thank you, @ratherbesewing. My fabricator has the old boards but I haven't chosen a fabric or embellishments (if any) yet. I think I'm leaning towards welting and no buttons. @arcy_gw, your wood cornice looks nice, but I'm recovering existing cornice boards and I really need the soft goods to help with absorbing sound in this large, mostly hard surfaces area.

Not sure why this picture didn’t post. Slightly curved valance.