There are 2 va bene caffes at the cosmopolitan. The one that serves gelato is in the 2nd floor near the chandelier.
I got the pistachio gelato and it was sooo delicious. For sure going to get it again if I stay at the cosmopolitan. It was a bit pricey. I believe it was $5 for one scoop and $7 for 2 scoops. We got the 2 scoops and took out one scoop and put it in a cup when I got back to my room :)