They have these Magnum Cafés all over Europe, but this was my first time going and it was a perfect treat to enjoy while getting lost in Venice. They have coffee and other treats, but the custom made ice cream bars are what you should go for.
When I was in Italy I had a gelato everyday. I went to this place everyday when I was in Venice. As far as I'm concerned it is the best gelato in the city. They have the standard flavours you will find at any gelaterie as well as their own unique mixes.
RIVA LOUNGE - GRITTI PALACE
This place gets a notable mention for the location, not the food. The lounge sits on the canal and is beautiful, you have the best views. However, it is super expensive. My friend had a 15€ coffee, and my bellini was 30€. You're paying for the location and ambience but one drink was worth it.