You pretty much have to do this when in Venice!
Going on a gondola ride while in Venice is one of those things that you are pretty likely to do, even though the prices are high. It's just a traditional way to see the city, and it's really a great way to see it, too. You end up on a lot of smaller canals which gives you a different perspective on the place.
We took off for our ride when sunset was approaching, and that always makes me a little nervous. While we did that on purpose, I am always scared that I will miss the lovely light. We started in the Grand Canal but quickly ended up touring through a myriad of smaller, empty canals and I was totally turned around. I have no idea how the gondoliers know their way around, but I guess it's like driving your car at home - you recognize streets and landmarks and eventually learn your way around the place.
Anyways, when it was nearing the end of our tour, I could see the light was getting pretty spectacular, and that was about the time that we ended back up in the Grand Canal, heading back to the dock. I had three cameras going, firing away with one and then another, until we were done. I like to think that I came away with something worthwhile. I certainly tried hard! :-)