I would do french doors that match the others.

That room has such beautiful windows and view that I would be tempted to keep the doors off altogether. But if you do want to close the room off at times, then I'd do something that you can see through because of that sweet view. French doors like pal mentioned or maybe something similar to the French doors but on a slider (like the 'barn door' slider style below.)

I have sliding barndoors as a front door! And to my bathroom off the mbr. But they wont work here because there are cabinets on either side.

I suppose french doors like the other DR entrances would make sense, but, same problem ... unless they make bifold french?

What about painting them to match the trim in the kitchen, replacing the glass with a slightly wavy restoration glass (like i have in my uppers).

maybe diff hardware, too?

Is there space on the wall for pocket doors?

You could install a pair of matching double acting pocket doors (both doors move when either is moved).

I have installed multiple pocket doors over the years to separate dining rooms from kitchens.

It takes no floor space usually 9like a swinger or bi-folds) but provides the option of closing the doors when desired (like after cleaning up from a meal when you want to hide the mess in the kitchen and still entertain).

The rest of the time they can simply be left open.

Yes they do make bi-fold french doors. A friend of mine has them!

Could they swing INTO the dining room, or be barn doors mounted on the dining room side?

No, because they they would occlude windows from the kitchen to DR/sub room.

See the floorplan attached (door opening under discussion is labelled #1 it so happens)

Actually, come to think of it, that also precludes pocket doors then.

Here is a link that might be useful: floorplan

I would do bifolds that swing into the dining room and fold flat against the wall--if you have enough room to clear the windows. Rather than being on a track they would have to catch on magnets. Look at Trustile if you can't find a glass bifold you like off the shelf

My parents have paired doors into the dining room that get closed less than once a month now, but that once a month it is important.

Brainstorming here....We are working with a smaller scale situation, a single door opening between kitchen and dining room, all on same floor plane, no drop down. We've put in a pocket for pocket door but it will be months before I know what it feels like to pull that door and how easily I will be able to pull it. A concern is always "will it open or shut for me if I try to operate it while I have my hands full?" We decided to put in the heavy-duty pocket door hardware just so that it would roll as freely as possible. Wish I could tell you how it's going to work, but I haven't even decided what door to buy yet.

Is there anything you want to put up on the wall on either side of the door frame, on either room's walls--furniture pieces or art? We didn't want the swing of an open door to eat up wall space so we added sufficient depth to the wall to allow a pocket door. This gave us wall space we needed on both sides of the wall. I wonder if there is such a thing as a multi-part door that has 4 sections that can somehow stack back into a narrow width pocket--it would allow you to leave the flanking windows intact.

Am wondering how often you will shut those doors and under what conditions--for privacy? control dogs? control kids? control smells? control sound? control light? to hold in heat? Will you try to open the door(s) while you're actually doing something else, such as toting food to and from the kitchen? Can you operate the door from the dining room side without balancing on a step? Would fabric serve the same purposes that a true door would serve? If so, you're home free--there are all kinds of interesting options out there for you. But if you need substance, fabric ain't gonna cut it.

Also, how hard is it to operate the folding doors you now have, from each of the two sides? Is there one step or more than one? Can you open or reposition sufficient area with a foot or knee or do you need a free hand or two?

Your folding doors don't look that bad, although the glass is not a good match with the style of the dining room. Could you choose a new glass to insert into the doors or are they slated to go away no matter what replaces them? We've seen lots of exciting glass options.

Do you have openable windows between the two rooms or are these window openings without windows in them, more like a pass-through?

Would an "atrium" door serve, which has one fixed and one swinging side? It would cut down the width of the opening, but would allow the view to show and the one door just folds back over the other door. This could be installed to open into the kitchen. In our community, I don't think building code would allow it to swing over a stairway.

Got lots of money and a good carpenter? I think I'd vote for a folding door somewhat like your existing door but attached in such a way as to allow a complete fold back from the door frame if possible--I think that my mother had window shutters that did this, folding back on one another when not covering the window but I can't remember how we achieved it. Maybe it's fantasy. I'd use multi-pane doors that echo the dining room exterior windows.