While the Grand Canal in Venice is the most famous, the numerous smaller side canals provide all sorts of artistic inspiration. Being narrower, there are often buildings in total shadow contrasting to ones in full sunshine. The reflections in the water, likewise, have strong lights and darks.
One of the problems with Venice is that there's so much choice, so much that would make a great painting. With a scene such as in this photo, do you include the blue-and-yellow mooring poles on the left, or crop into the scene to focus on the bridge and church tower? You could crop it so you've shadow on both edges of the scene, or so you've light on the left and shadow on the right.
When Whistler was in Venice, he did quite a few pastels (done on brown paper) and etchings, some of which focus on small scenes. Often he left a lot undepicted, merely suggesting buildings through a few lines. (There's a book on his work from Venice, see my list of books on Whistler.)
