I would come to Vegas just to see these fountains, because they really are that gorgeous and you are sure to get goosebumps from watching these fountains. I was in Vegas for about 4 days and every day we made sure to stop by at night just to watch them. They are breathtaking!! Definitely a must see whenever you're in Vegas.
One of my favorite performances is definitely Faith Hill's "This Kiss"
http://www.youtube.com/watch?v=F_chylF1wGw