For the gondola ride, you will see them in various parts of the city by the hotels. In some areas (like the Bridge of Sighs) they will be lined up. Very magical. Oh, it's extra to have music (Accordian!)or singing. Our Tauck tour included a gondola ride and they took us out to the middle of the canal about 6 people per gondola, lined us up side by side, full moon and we were all singing. Fun!
Our favorite day was wandering the streets and our dinner on the rooftop of the Hotel Daneli.
Editing to add, we get on the Voyager as you debark. See you on the Gangplank!!