I was in Venice one week after the worst of the recent floods. We were worried that it would be like visiting a disaster zone, but it wasn't at all. There was only a little evidence that anything out of the ordinary had happened the week before. Only a handful of businesses were closed; the vast majority of shops and restaurants were open for business as usual, as were all the "sights" that we saw. Some buildings showed signs of having sustained more lasting damage (to floor tilework, etc.), but there was nothing that had much of an effect on our experience as casual tourists.
By the way, the water level is measured with respect to a "zero" that is well below the street surface anywhere in the city. St. Mark's Square, the lowest point in Venice, only begins to flood when the water level reaches 80 cm, and ground level in other parts of the city is significantly higher than that. So when you saw reports of the water level having reached 187 cm (a bit more than 6 feet), that doesn't mean that Venice was 6 feet underwater. At worst, it was 3 1/2 feet (which, to be sure, was bad enough). Here is a good illustration of what the tide levels look like at various points in the city.