Casa Verde is a Venetian dream. It's quite, well located to the biennale (4 minute walk), newly renovated, very clean, tastefully decorated with delicious breakfast every morning & a outside garden.
Veronica is a gem with amazing warm precise hospitality. I'd recommend this place to anyone & everyone visiting Venice, especially if your sole purpose is the biennale- she'll give you advise on all the must see during your stay.