On the one hand, dressing up for Las Vegas is a no-brainer: it's 40 degrees (Celsius) in the shade there during the summer, so shorts and a T-shirt is all you need. On the other hand, American establishments are known for blasting A/C on maximum throughout the summer and it's not like you'll spend a lot of time out in the sun anyway.
So what kind of clothing should I pack for a visit this August?