TLDR: IMAX available; semi-filled concession lines; great theater temperature; bathrooms near entrance
Regal Cinemas is located inside the Red Rock Resort Hotel & Casino adjacent to the food court and bingo hall. The concession stand is located just after the ticketing desk but before the ticket collector at the theatre rooms. There are IMAX viewing rooms available and restrooms only located near the entrance. This doesn't allow access for a quick pee break of you're near the end of the hall.
The concession stand has better service than before with their new sales pitch asking for a large popcorn right before you approach the counter. The menu offering is much larger compared to other Regal/Edwards/United Artists locations with their lavazza coffee and freschetta pizza so if you're in the mood for a coffee, then go home and watch Netflix. :)
The theatre experience is favorable. There's a lot of seats for both the privileged and the handi-capable and the ambient temperature is comfortable, even in shorts. All-in-all 4 stars!