To start with, it's a crossing. You are in a refined environment, so you decide what you would wear given that, and not what you see some other passengers do.
My idea is not to dress down, because that is what I do at home, but to dress according to the setting, which is different.
Guests may feel that they can walk up to the Front Desk at the Waldor Astoria in jeans, but I never would. Art Deco is high style and jeans and tee shirts denigrate the ambiance .