We did a 12-night Mediterranean cruise from Barcelona to Venice in 2014. We actually pulled into Venice the day before the cruise ended and had a night in port, so that there were Port Adventures offered that day. The only issue with this was, that the night before we pulled into Venice was treated as the last night for show and dining purpose, leaving the true last night as kind of a let down, with many people not returning to the ship that night or departing outright that day. The PAs offered in Venice were a wide variety, and we did had a tour of St Peters Basilica, Doge's Palace, the Grand Canal, and Piazza San Marco. Following our cruise, they ran several 7-night cruises out of Venice, and finished with an 12-night back to Barcelona.