Close them over then do what ever you like on those walls .Please no vase with fake whatever .

We have several art niches, some shallow and others deep. For ideas here are various pix with comments

Large tile back

Tile back with projecting bottom shelf

Painted back

Painted back

Uplit painted back

If in my home they would be drywalled over so I could hang nice art there.

How deep are the recesses?

If the budget permits, I'd sheetrock over them. If not, I'd add artwork in the shape of the opening - so that the art fills most of the back of the niche. I wouldn't want to highlight it with different paint, tile, etc - that look can appear dated.

I kind of like the floating shelves idea!!

You could also just hang art within them.

I like wall niches!

Mega cool would be a backlit onyx slab.

I drywalled over two of mine but they were much larger and truly awkward. Though I’m not a huge fan, still, of niches, I do like the floating shelves look. I like that color wood, too. It would depend on how well the shelves tie in to the rest of your space, but I bet it could be attractive.

I e would like interesting tapestries or fabric art

If you want to, you could try drywalling over them, and then hanging a nice piece of artwork.

Designer Showhouse · More Info

If you don't want to do that, you might try adding some shelves and decorating them like this:

Colonial Style Home · More Info