Not sure what the C of S site is...did you mean
https://www.cirquedusoleil.com/usa/las-vegas/deals ?
You can use their site to find discounts. I also use smartervegas.com or travelzoo.com.
For any of those sites, clicking on a link there has always redirected me to either ticketmaster or to a page on the hotel's site & applied the discount automatically (you always have options to verify seats & prices before checking out). So if your concern is making sure you don't get ripped off, make sure you get redirected like that. If the concern is more logistics, like how do you get physical tickets, there are several options. Looks like the default these days is now email only. For an extra fee, you can pay to have the tickets waiting for you @ will call. The box offices will generally open an hour or two before the show.
That being said, you can sometimes find better deals once you get to Vegas at one of the discount ticket booths (like Tix4Tonight). If you know the shows you want to see, and you're going during a busy time, the savings probably aren't going to be worth the extra hassle though (there's always a line).