There's only a few reviews on this place so I'm guessing it's relatively new. I'm a huge gelato addict. My personal favorite is at Illy Espressamente inside The Palazzo which serves Cocolini throughout The Venetian as well. But after paying $6 for a scoop, I decided to go hunt for somewhere that may be a little cheaper.
Zio Gelato is located in what appears to be a hidden location on the far side of The Venetian in the hallway behind B&B Burger and the Sports Bar. I got a scoop of the hazelnut which I paid $4.00 (plus tax) for. Since I had the gelato from Cocolini exactly the night before, I can definitely say that the gelato tasted very comparable. Since there are a few mixed reviews of this place, I'll just assume that not all their flavors good and they don't have as much variety.
Still - I thought the hazelnut was delicious and a pretty good bang for my buck, at least for Vegas Strip prices. Servers were also very friendly.