The Venetian runs gondolas on two separate waterways, and they are genuinely different rides. The indoor route goes down the Grand Canal through the Grand Canal Shoppes, beneath a painted sky ceiling, past St Mark's Square and the shopfronts. The outdoor route circles the lagoon at the front of the resort along Las Vegas Boulevard, which is the better one after dark.
Rides last about ten to fifteen minutes and your gondolier sings. Boats seat four, so a standard ticket may put you in with strangers; a private gondola books the whole boat. Tickets are priced per person either way.
The indoor canal runs latest, to 11:00 PM most nights and midnight on Friday and Saturday, while the outdoor gondolas stop at 10:00 PM. The last boat departs fifteen minutes before closing.