Whenever I see tall curved walls like yours my first thought is wallpaper. Honestly- what else could be a more perfect solution? In one day a wallpaper installer could add some serious personality to your space. I would select a pattern that gave a glimpse into your home's personality.
I love the rhythm that you get with the movement of these branches:
In your empty curved space I would add an entry table with a potted something or other on it.
This table is 47 x 31, nice and narrow, but still long enough to not be too small from a scale standpoint, and large enough to add a large plant.
I am also a big fan of the fiddle leaf fig, as well, but I think your entry needs more than just a plant.
You could also add a smaller table with a chair or two:
Depending on the size of the space and the furniture, you could do the same thing with one larger chair:
Since Mother's Day is around the corner, I will tell you what to ask for: A fabulous runner for your staircaise. Talk about a huge difference. This would look awesome!
Then for Father's Day you can add the slide ;-):
As far as those "niches" go- I hate those things. I'd have it filled it. I think they take a lovely space and make it look cheesy and cheap. I see them in million dollar homes around where I live all the time and absolutely dislike evey one. And yes, your sconces are way too small for the space, but once you put up your wallpaper- you won't need anything else. If you want to go all out- you could add wainscoting and wallpaper.
Your entry has a ton of potential. It was clealy built to be a great first impression. Remember that your entry is the window into your home. It should tell a little something about the people who live there. It should welcome not only guests, but also your own family. Ideally it is the space where your children enter and feel safe and happy. Give it some real thought and consideration. What feeling do you want to envoke?