For Venice, Foresteria Valdese was awesome. It's run by the Methodist church, no curfew, but they do lockout from 12pm-4pm for cleaning. It's very popular (only hostel on the main island, fantastic location) so book early. Here's a link: http://www.wcities.com/en/record/,76422/29/record.html
Smallish free breakfast, but there are a few grocery stores/bread/cheese shops nearby.
The other hostel is on Guidecca (sp?) island and is noisy and crowded.