I would use it to create a tableau of favorite knick-knacks and family pictures. Also, find a few small items you like to hang from the top of it, like candle holders, tussie-mussies, etc. To create levels, stack things in the back on a pile of beautiful hard-cover books.
If that's too busy for your personal style, you could also find an old window, preferably with multiple panes, and hang it flush with the front wall. I had a similar niche above my fridge, and hung a window with four glass panes (striped, not squared, with a different dried herb hanging behind each pane. Created the illusion of a wall, without having to dry-wall, etc. It allowed me to store vases, pitchers etc. behind it, without it looking cluttered.
Last idea - try hanging a trio of paper lanterns. You can gte them in all sorts of colors and shapes these days. PIck three of the same shape in colors to complement your decor, or three different shapes and sizes.
