Is it possible to get tickets (at the usual price as oppose to the “black market” price) for O or Mystere (Cirque du Soleil) eventhough the website showed it is sold out? (or website indicates only limited view seats are available)

If tix are sold out, there are 2 ways that i know of that you can still get tix at face value:

1) If you have a relationship with a casino host (at any hotel) they may be able to get you tickets (if you don't qualify for a comp, they may do it as a courtesy if you're willing to pay for them)

2) They release "held" and cancelled tickets about 2 hours before showtime, but the line for these tickets starts late in the morning/early in the day. Not the ideal way to spend 1/2 a day of your vacation, although it is an option.

For either method above you may use, i would think that Mystere would be easier than O since it's an older show. Also, don't know when you are looking for tickets, but if it's near the beginning of Dec, lots of shows are dark for two weeks in Dec, so they may actually be "closed" and not sold out.

I've seen these tickets on ebay many times....have you checked there yet?

You can get decent face value tix by standing in line before the show as above.
You'll pay really exorbitant prices thru the ticket brokers.
Mystere is a lot easier than O.

I had a good experience getting tickets to "O". I printed off a seating chart from the hotel web site. I called the 800 number listed. I was told the show was sold out. This was about a month prior to my departure date. I kept calling every day and I ended up getting excellent seats for the show. I was told that, unlike many of the shows , "O" has a 24 hour cancellation policy. I had reservations before I left for Vegas. You might try calling every day or two before departure...