Best time to visit Venice must be December! You can move around without being squashed! It is a bit chilly but the fog/mist in the morning makes for very moody photos. I did a lot in B&W which I really like.
This has the feel that it could have been taken anytime in the last 60 years!
Getting up at 5:00 in the morning gets you to roam around Venice and have the streets all for yourself.
Also got a nice Colour shot of the classic view in Venice. This taken with my little Ricoh GR
2 minute exposure
Here another shot I liked that captured the mood early evening.