-- How about another silk tree in a fabulous pot! Add a colorful Persian rug and some artwork going up the stairs. If you don't have one already, a chandelier would be awesome too.

I agree, a good quality silk tree in a great pot would be the best solution

You could hang a picture or a piece of art on the straight wall and a tall tree to fill in the empty space.

inspiration pic
a small etagere filled with yr favourite things [just not too many of them:) ]

Team Nolia would go another direction. How about a piece of white onyx, cut to shape with illumintion from below? The size is so small, you could find a remnant stone, and any stone cutter to cut from the exact template and install. Hire an electrician or just some DIY cabinet lights and voila! A beautifully highlighted area for family treasures or seasonal decor. Contact with any installation questions: inquiries@noliadesign.com

How about a colourful rug, floating shelf against the flat wall and artwork or mirror above the floating shelf. You could add a basket or stool under the shelf.

Sculpture. (very nice, Nolia)

Thanks everyone for your help!! The ideas are great!