I can’t speak to a lower floor, only higher floors. If you are really observant and don’t have other things like the HVAC, etc on you can occasionally ‘feel’ an oh so subtle vibration when the express monorail is running through. Although I’ve really only noticed that when it’s dead quiet first thing in the AM when you can pick up on things and most aren’t going to notice. When I’m in the tower I worry more about general atrium noise than the monorail, personally (which is why I usually request to be on the north side of the floor away from Chef Mickeys).