While I don't like to see dress standards dropped entirely, I agree with colorcrazie. I get weary of self-righteous threads that discuss tux with tails, top hats etc. Do we really want to put cruising back into the realm of only the rich and famous? Perhaps those men who are only wearing a very nice sport coat or dark suit could promise to remain in 'steerage' and leave the dining room to the grander, self-important group.
You will be fine