I like the idea of making the railings darker so the curving line of your staircase is emphasized. I would paint the balusters white to match the trim.

I think the stairs themselves match your beautiful hardwood flooring in the two rooms flanking the hall. I think there's a disconnect between the stairs and the marble floor however.

Since you are removing the marble, I would recommend laying a hardwood floor in the foyer. You could have a border around it of a very dark hardwood and then do the middle ground in a wood closely matching your existing floors. You could buy unfinished wood for the ground and have your installer stain on-site to match the rest of your hardwood. Then the stairs and the floors would relate to each other better. I would put a beautiful persian rug in the foyer, as big a one as will fit there.

If you want an alternative idea, I would recommend a black marble floor with lots of white veining for a very classic look. Then I would paint the risers white and the treads and railings black. (Or the railings could be stained black.) I would put a big Persian rug on this too!

The new chandelier should have black on it somewhere, even if just on little lampshades. In fact, brass is coming back in a big way, and you could update your fixture by putting simple black shades on each of the bulbs. Go to a good quality lighting store that can order you some nice ones.