While I have been to Venice, and I did purchase traditional venetian Carnevale masks while there, I was unfortunately not there at the right time of year to actually attend Carnevale. :/
The mask shops in Venice, even when it's nowhere near Carnevale season, are absolutely spectacular. We brought back two traditional Joker masks;
(VV Joker Style VV)

And I bought a plague mask for myself, and we brought back some smaller colombina masks for assorted family and friends.
I'd love to be able to go back one day specifically for Carnevale, and just because Venice was a magical place to be. :3