we are gong to the show Mystere in Las Vegas. I read on one website that the dress for shows in Las Vegas is semi-formal...men in dark suits or even tuxedos and women in fancy cocktail attire. Does anyone know if this is how we should dress for this show Or others we might go to?)

I cannot imagine what website would tell you to wear a tux to see the Cirque de Soleil!
We have been to all the shows in Vegas, if you want to be dressed nicely, wear something black. Pants are fine.
Men hardly ever wear suits, he can wear a shirt and trousers.

I am going to "O" Saturday and I am wearing a "little black" lace dress topped by a black sweater that has ruffles around the collar, bottoma and sleeves. I am then wearing high leather black boots with a little pattern on them and a black choker with a white cameo on it. My husband will NOT be wearing a tux.

Perfect!! Have fun, "O" is very enjoyable!

We did Mystere last Thanksgiving and wore dressy casual (if that makes sense). My husband wore nice slacks, Jhane Barnes sweater and jacket, and I wore Navy pants and sweater outfit with a favorite pair of funky Icons. Everyone was dressed nicely, but I didn't see any formal or semi formal. Can't speak for other shows--that was the only one we did.

When I say Mystere people dressed in shorts, some in slacks. Anything is acceptable.

Gimme a break!!

Are you kidding???

Tuxedos and black evening dresses???

We went for Thanksgiving this year and most people were wearing jeans. Las Vegas is the "King of Casual" to begin with.
Put that together with the national trend toward casual everything and you get "mall dress" even at the better shows in LV.

I think that high school proms are the only place in the US today where you may find most of the guys in tuxedos. Certainly you will not find them routinely in Las Vegas. Just bring a sweater for the hyper-active air con. Of course, if you do dress up, it would be classy

I absolutely cannot imagine a website that would seriously suggest anyone wear tuxedos or dark suits for a show in Las Vegas. I've never seen one single person wearing a tux to a show, and I'd have to think hard to remember when (or if) I've ever seen a man in a dark suit. Nice pants are fine for women and coats are nice (though unnecessary for men).