i think crowd avoidance is the main issue in venice. we prefer feb,march,april(until carnivalE). then after carnivalE is also good. high water is a minimal problem. the temps are not that bad, particularly when compared to the mobs of summer. snow is very bad when it happens. no one moves it, and the steps over bridges are very difficult.(happens about once every few years).
pretty much everything is open these days, so no museum or feeding problems. hotels are empty, and rates are lowest.