We (a couple with no kids) have just returned from Venice and here are some thoughts on the places we ate at:

Al Covo (dinner) - wonderful food and great service.
Osteria alla Frasca (dinner) - less formal than Al Covo, same quality of food, great pasta
Vino Vino (lunch) - good for lunch, especially if you are in the area
Trattoria da Romano on Burano (lunch) - great seafood risotto made with the Gó fish stock
Locanda Cipriani on Torcello (lunch) - amazing old school restaurant (most formal and most expensive out of all places we have tried in Venice).
Ai Cugnai (dinner) - some items on the menu are surprising (not typical of Venice) but the Venetian dishes we had were good. I wouldn’t go out of my way to get there but if you are in Dorsoduro, it’s a good choice

We have also tried several ciccheti places (Do Mori, All’Arco, gia Schiavi) and found gia Schiavi to be the best and the least expensive.

bottom line: Venice has amazing food, you just need to know what to order where. Wines from Veneto are also very good and pair perfectly with local dishes (obviously no surprise here)