My family (5) and I just got back from Venice. Before we went, I reviewed these forums for advice and now I just want to add a few things, right now about Gondolas, that I missed.
Don't prebook a gondola tour. We did. It was very impersonal. There was a stranger added to our gondola to make the number of passengers, six. The gondolier seemed burned out, chatted with all the other gondonliers we passed, but mostly ignored us. The group of gondolas in the tour followed each other, wagon-train style, and the whole thing felt like, and was dubbed by my kids, "the Disney ride."
Don't get me wrong, the views from the small canals and Grand Canal were great, the architecture amazing, and, because it was preseason and not hot, not smelly. The gondola was very well kept.
Anyway, the next day, we wanted to try a gondola again.
I learned they do not operate like taxis, as I rather expected. We tried to get a gondolier to take us to a wine bar we had visited the previous day. He would have, but at 120€, we figured we could walk and use that money for wine.
However, the gondoliers seem, instead, to have a fixed, 30-minute loop they like to use (which varies based on the gondolier, time, and location) for which they charge a fixed price, 80€. This loop ended up being closer to 40 minutes and was definitely more distance than the "taxi" ride I had initially asked for.
This time, the gondolier engaged us in conversation, chatted about the sights, and generally was friendly and personable. We enjoyed the trip.
We selected the gondolier at a stand near the Rialto bridge. We chatted with a couple of gondoliers, went on the tour, and came back to the same spot. While I would not use a gondola again, because of the expense, you have to the first time and, if you do, I urge you to not pre-book a tour. Just go to a stand of gondolas and arrange the tour in person at the time you want it.
Sean