One of the bucket list items to see when in Vegas. The fountains are a spectacular show to see for the first time. The music with the bursts of water from the fountains is fantastic. The best time is to see it at night as it runs once every 15 minutes.
I've only had a view from Vdara a couple of times. I've also been to a couple of restaurants that had views as well. It's very cool to see from afar on top. I'm sure Cosmo and at the Bellagio is just as cool.