Wine tasting suggestions in Venice?

In general I wouldn't recommend a wine tasting Venice because it's an island and they don't make any wine there so basically you'd be tasting wines produced elsewhere. This means you're being way overcharged for them to open wines bottled elsewhere in Italy. If you're only going to Venice and want to experience it then fine, go for it, but if you're going to other parts of Italy, cripes, do not do a wine tasting in Venice. It'd be like ordering lobster in Kentucky.

 IMHO do what the locals do. walk into a cicchetti bar order the house white and a plate(s) of whatever you like. If you pick a lively place in the late afternoon it can be a mixer.  Make sure to have in your phone a photo of Ranier & Space Needle to show if they ask where you're from.  As per SOP avoid English-only speaking crowds and menus printed in 5 languages. Cicchetti bars/enotecas are all over town but the most fun I've had are not nearby the Piazza.  http://mg.co.za/article/2010-02-19-romancing-the-cicchetti     

Just wondering around we stumbled across a great shop that had a variety of wines in big casks. You could taste by the glass or have them fill a liter bottle for just a few euros. It was in the San Polo area. We'll be looking for it again when we go back in March.

If you find the name, please let me know. We leave in 3 weeks and that sounds like fun.

Rick
I appreciate your feedback! Thank you! We plan to make a pitstop in Florence ...maybe but then on to Rome. Any suggestions? For wine tasting their?

Otariidae !!! Thank you!! Did you try these places? I wrote all of them down and planned on seeing them instead of hiring a tour from Expedia.
Thanks! I will post my experiences:)

After a few hombre I cannot not swear to this but ...  Do Mori some nights empty other times full of Eurofolk and locals and some Americans.  If it is empty go in anyway a try it.  The owners recommended a few other spots  Cantinone-gia Schiavi sometimes overrun by folks reading guidebooks.  Other timess a great mix of locals and others Campo Santa Margarita, cafes all over and a good hang out.  Do not recall any cicchetti and I lost count of the spritzes. Try a spritz with aperol. 

What Nan described above is a part of everyday Italian life, it's called "Vino sfuzo" which is basically wine on tap. It's priced by the litre and it's how most Italians get their wine since it's cheap and they buy so much. We get most of our wine this way as well. Pretty much every town has at least one. There are several in Venice that I've seen and if you don't have a glass bottle you can use an empty plastic water (do not use empty juice or soda bottles for the obvious reason).