I rather dislike some of the posts venting on hotels, car rental, venues, etc. Sometimes people's expectations were too high, or there was blame to go around, or there was an honest mistake. But, so, here, I go. My intent is to caution folks so that they can decide how they'd want to structure an itinerary. On June 3, I booked Palazzo Pisani (Venice on top) for September 20. Today, August 1, I got an email that said they were processing my cancellation request. Except I didn't cancel. Turns out, Tiquets overbooked. However, I booked on one of the first days tickets went on sale, if not the first. So, they made an error and it took 2 months for them to figure it out. Customer service could offer me no help except 5% discount on a future booking (laughable). There are only two of us. Hard to believe that they couldn't figure something out if they wanted to. Fortunately, I can book for another night, though I have to revise my itinerary.
So, use this information as you like. I'm not sure if this is just some fluke or a frequent occurrence. I don't ever double book hotels or venues. I just don't think the practice is fair to the business or other customers. However, if Palazzo Pisani is very important to you, I'd watch your booking and their calendar. Perhaps, double book, because they do allow cancellations.
I'm not saying Tiquets or Palazzo Pisani is a terrible company and no one else should book it. I'm just suggesting some caution. For me, I've resolved the situation. I only book venues in advance when I need to, and I work hard to not book activities tightly, so I had some wiggle room. I can't say I'm happy with what happened or how they choose to handle it, but I'm good. Life goes on and I'm grateful that I can travel to wonderful places.