I've been to Venice twice but only for the day each time, I'd love to stay and see in at night. Those pictures are amazing. I've been in August, whenit was very hot and crowde4d and at the beginning of NOvember when it was not quite so hot, still warm though and almost as crowded.
You're right, it costs a lot to go to the toilet and the gondolas are really expensive too. There were 4 of us when we went in November so we got a water taxi instead whihc was a lot cheaper and much more exciting, we felt like we were in a James Bond film