Decorate this empty space ?

Add a bunch of houseplants

That would be great for a bunch of books!

A few house plants (possibly fake), a few family photos. A variety of decorated vases in different sizes. Have some kind of collectibles?!

Since it is in your dining room I would suggest finding unique serving pieces such as a soup tureen, coffee/tea service platters, antique chargers, etc. Or find a mural that would fit the alcove and tie in with your style.

Oooh, you can do some interesting things up there! How about a piece of stained glass with a light behind it? Hang it forward so it lines up with the rest of the wall. Or, create a long rectangular piece of artwork that is BOLD. Hang on the wall or moved forward if needed to see it well and put up battery-operated lights to cast light on it.

Not knowing your style, you could put sculptures/dolls/ things with "legs" that sit on the ledge and hang the 'legs' down the wall. Add pieces that go with the "guys with legs" below on the main wall.

You can get some cheap up lighting at amazon. I got a 3 pack of led lighting for under $20. Install that and this would a great place to display items you don't want little hands grabbing or breaking like ceramic vases etc.

If you put plants up there you will just be dragging a ladder out to water them and if they over flow up there now you have a mess.

you could paint it an accent color or add wallpaper to that area to give it a pop of color; you could add candle holders and candles, you could add antique plates or even tea cups or pots there.

The idea of accent color by Cheryl A is a good one, similar to an accent wall in a house. Another thought is to use peel and stick wall paper/contact paper as a texture rather than a scene that you might have trouble seeing in detail. Something like birch logs or just a background would work well.

I think it depends on the room and your style, but I would opt for a few white serving pieces, clean in style. They won't compete with other elements in the room, but will add an interesting view.

I have an alternate idea. What about hanging something over it (then no dusting!). I’m thinking like a tapestry or quilt on a rod or something like that. :)

Hi Mandi, here's a link to some general info about decorating niches although most them show vertical spaces rather than horizontal as yours is. I hope one of the pictures/ideas might inspire you. Lighting seems to be key, so if you could have an outlet for lighting installed with a wall switch that is handy, that would be a wonderful start to what could become the showpiece of your room. Hve fun!

https://nextluxury.com/home-design/recessed-wall-niche-ideas/

You can use plants there

Hello. I think it would be an excellent place for displaying a collection. If you’re more of a minimalist it might be harder. Sculpture- art pieces or antiques- baskets -clocks might be some options to consider.

Keep in mind that anything you do put up there will collect dust like crazy.

I would suggest that you not put items that are difficult to dust, or

or that might fall off and break easily in the process.

Decor is a personal choice. Depends what you like. perhaps start with painting the back a different shade/color... Like we have a farm house and we use some old milk cans and some big bean pots on a ledge....

Put some pretty depression glass up there or family pictures all kinds of frames

I see a row of about 4 cute baskets up there. Then you can use it to store things that are not used very often.

Hi,

Use Plants, Real or Artificial. Frame around the outside and then add nice things.

What about using it to do seasonal displays? Take time to hunt thrift (or retail) stores for large beautiful Fall/Christmas/Valentine/ etc. decor. Don't put a lot of little items, but just a large ceramic pumpkin on a bed of fall foliage, or a few large nutcrackers or Christmas Village houses, or an Easter Basket and bunny, etc. Also, have one set of decor that works for any season like books, plants, plates, or baskets that others have suggested. A couple of low chunky candle holders that hold large candles could be used on either side with one of the items just mentioned and you can change the candles out seasonally. (Obviously these candles are not for burning, but just for color.) You have such a great opportunity to add your personality to a this space.

Maybe a gallery wall of family photos

I found this info for you

https://www.pinterest.com.mx/salryan11/nicho-decor/

Plants! Either low-maintenance live plants or pretty faux.