Of course, in Vegas there is always the FREE entertainment and then there is always the entertainment that you pay for. This is about the entertainment that we paid for (aside from the buskers--I paid a dollar, but they were raising money for habitat for humanity).
We went and saw Ka by Cirque du Soleil.
Production-wise the show kicked ass. For those that don't know, Ka is performed on a stage that floats, twists, spins, goes vertical, goes horizontal, and sometimes isn't even there.
'Cirque'-wise, the show was very 'meh'. There was really only one act that seemed to push the realm of what the human body can do.
We sat in the back of the theater (there was only one row behind us), but for the most part we could see everything and it wasn't a problem. The only time when I would have liked to be closer would have been during the beginning fight scenes as from where we sat it was pretty boring. And I think a lot of it was because we weren't close enough to see all the sword and staff work.
I would suggest seeing it, especially if you haven't ever seen any Cirque Show. If you have seen a Cirque show, know that this isn't going to be the same type of thing--prepare to be entertained, but not necessarily wowed.