Never checked luggage. There are porters. They are hard to find, but they are about. Venice has carts. You can wheel your luggage from the boat stop to the train car. The ends of the Euro Star first class compartments have storage space for luggage, and overheads. Venice is on level ground. Many of the stations are not. Have not been to Florence or Rome station, but Bologna and Genoa require stairs to get to the train, and there is a tendency to switch tracks every now and then, which requires another romp down and up the staircase.