On a recent visit to LV, we saw "O" at the Bellagio. I've seen numerous Cirque productions over the years, but this fast became my favorite. A stunning piece of theatre and music. Tickets were expensive, about $300. for two, but we had excellent center seats midway up from the stage. A memorable experience.
Note: Do not miss the beautiful garden in the Bellagio with its representation of the Isle of Capri. Precious.