Venice is a place to walk and to explore. Everywhere, indoors and out, there is art. It is important to look up and around as you wander. It is not a place for anyone who cannot walk or climb stairs.
St Mark's Square is the famous central point, well-known for its thousands of pidgeons. In the summer, the square is obviously filled to the brim with visitors, but in December it is vacant. There are at least 7 major historic places around the square, making it a wonderful central point to begin your exploration of Venice.
The weather is fine. You just need a light jacket and a small umbrella should the day turn poor. We were there for 7 days and never had a really bad day. The real benefit was not contending with the millions of other tourists that visit during the summer months.
Quick Tips:
At breakfast each day, plan your walks so that you eventually circle back to your hotel. You can efficiently cover all parts of the city this way. There are hundreds of food options in the town and some of the best lunchtime pizza we have ever had. Treat yourself to a good coffee and pizza. This will give you the energy to keep moving.
Best Way To Get Around:
Walking, Walking, Walking. No cars are allowed on the island, and the canal boats are limited as to where they land.