This thread has good away from a few quick recomedations and has become a worthwhile go to resource. I'll add a few more of the places I go more often than others.
Chengdu Taste in Las Vegas is very good. It's kind of on the back side of Chinatown. I don't think it's as good an example of Schezuan as LOS or Chada Thai is for Northern Thai, but that still leaves lots of room to excel.
http://www.chengdutastelasvegas.com/
Very extensive menu. I can recommend the Chicken in Hot Chili Pepper, Whole Fish cook in Hot Chili Pepper, Geiger Scallion Lamb, Hunan Spicy Lamb, Hot & Spicy Pork Belly, and Duck in Beer Sauce.
There is often a wait, but it is usually fairly short. They provide a pad and those waiting organize and keep the list. Lots for friendly chatter among those waiting, who are often from all over the world. A great place to compare notes with others on where to get quality Schezuan in other cities. Prices are quite reasonable, too.
District One in China Town is good, too. Not as much to my taste. A bit more cosmopolitan/Asian Fusion sort of place. Emphasis on Vietnamese food. But still good and quite inventive. Emphasis on sea food.
http://www.districtonelv.com/
Another place if you like seafood and don't mind taking a long schlep away from the strip or downtown and heading way west -- quite a ways past China Town -- is Other Mama. Reservations recommended. But incredibly fresh and inventive seafood. More expensive than District One. But quite good.
https://www.othermamalv.com/
Twist by Pierre Gagnaire, in the Mandarin Oriental is pretty extraordinary. But it is VERY expensive. If we're getting into this luxe Three Star price range, which restauant you pick becomes a very personal choice. I haven't eaten at all the ultra luxe places in Las Vegas. But the ones I have eaten at Joel Robuchon (not Atelier du Joel Robuchoen which is much more reasonable), Twist, and Sage, I prefer Twist. I think it's a tad less formal and the food is equally inventive. And just more to my taste. Also, I think the wine list is a bit more interesting and has less of a markup.
https://www.mandarinoriental.com/las...-gagnaire/menu
I haven't tried it yet, but I hear wonderful things about Black Sheep. I plan to eat there on my next trip. Vietnamese. I don't know where it is, but I'm told it's a long way from anywhere you are likely to be. If you're dining alone, your cab fare will likely be as much as your dinner tab.