Luggage and bags:
bring a backpack (especially if you are only staying for one day)
Clothing/Shoes/Weather Gear: Bring very comfortable shoes, and if you're visiting in summer, hot weather, wear light clothes, light colors, sunglasses.
Miscellaneous: This is a beautiful aerial view of Venice. You can see the Basilica of S. Marco, the big tower, the Palace of Dodges, many small houses, and part of the canal