Your room is terrific! Your wood cubes are fun but I am not sure that they work in that space. I'd like to see you add something round there - a set of mirrors or shallow baskets. Perhaps echo the round shapes on the other side of the fireplace as well. Larger round items should fill the space nicely and I don't think you'll feel the need to put something on the ledge.

Plus, that little ledge looks like a terrific play spot :)

Have you considered covering the ottomans in a muted kilim/tribal rug pattern?

How about an aftrican mask on the wall to the left of the fireplace. That is all it needs IMO

I think it's great as is