After long walks on the strip at night, it's always great to stop by and catch a show!
While not as advanced as Disney's California Adventure's World of Color show, the overall summer/night-time atmosphere at the Fountains of Bellagio is pretty amazing.
Like Justin N. mentioned, I'm sure a fountain view room would be a great place to watch the show as well. Definitely recommend to watch a few times if you're in Vegas :)