I wouldn't close them in because they probably offer a lot of light and ventilation. I think the options would vary on the style of the house and the decor style you prefer. Maybe you can put hangings there, old windows, painted glass

I agree about the light as one side of the wall faces north.

Thanks for the suggestion. We had thought about that but wasn't sure since each section seems kind of large, but if we found some interesting painted glass windows, it could be interesting. My other thought was maybe some kind of design using beams but I'm not that creative. I kind of have to see things. Thanks again!

I'd have to see pictures to decide, but at first blush, I'd opt to leave it open. Perhaps it has to do with how the top of the wall is finished.

If you go to houzz.com, and search on "partition wall" you'll see lots of ideas of how a wall can be completed from wood slats to plexiglass panels to open screening to etched glass or fill it in with bead curtains:

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or vinyl decorative lattice panels.

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Any number of options, though I'm thinking leaving it plain would be fine.

If you want a more open feel you could remove the 9' wall or do what they did on Meg's house by adding openings in the 9' wall and then installing framed windows top and bottom.

Glad it helped, and I hope you post a pic so we can see. Love that second pic Annie posted, quite clever and pretty.