Exotics Racing at the Vegas speedway is a blast since you'll be renting a car you can get there easily.
https://exoticsracing.com/
That's the must for me when I go...
Hoover Dam for sure if you have time and as others have suggested, Cirque du Soleil, wander around the strip and see if there are any other cool acts in town you want to see...
Dueling pianos is cool at New York New York...