Venice

Haven't used that site, but we have stayed at Pensione Guerrato several times. I believe they also have a small apt. to let in the same general area. Based on our experience staying with them at the pensione, we would not hesitate to check out the availability of their apartment. Hope this helps.

I have not used that site but have successfully used Home Away and VRBO in Venice. Between these two sites there are a very large number of apartments from which to choose. You might want to check them out before you go with a company about which you have doubts. Slow Travel Italy also has independent reviews of a number of apartments in Venice.

Booking.com also lists apartments, filter your search.

We used Airbnb and reserved a lovely room in a great location in Venice.

I used cross-pollinate for our recent family trip. We rented a beautiful apartment in Canneregio. I'd use them again.