It take us 1:20h by private shuttle from Genoa to Milan on a Sunday. It was not one excursion, it was the end of our cruise and we wanted to spend 3 days i Milan before returning home and we booked one shuttle for it. We could also go by train, but sometimes there are strikes in italy and we chose the shuttle instead because we were 9 adults
This was last November and our ship was far from Genoa port, we had to go by shuttle from the ship to the cruise port; we were there again (in Genoa)one week ago and our ship was near the port this time.