NO flowers at all.

I agree that the space does not need any flowers. There are enough detailed decorative elements already.

I would remove the pillow, it looks like it crowds the chair to me. I would put something tall and narrow in the corner at the bottom of the stairs. Perhaps a fancy but empty vase?

A light colored throw across the chair would go along way toward unifying the look and softening the graphic impact. The graphics on the table are a bit distracting. You might want to go bare or smaller and solid black.

I agree that it's way too matchy-match. The pillow is okay, but those boxes make the table look like you're having some sort of party, and that's where the guests are to put their gifts.

A flower arrangement with some red in it would look nice where the boxes are.