The word that I have heard is that Las Vegas is low on the priority list because we get a very strong good HD OTA signal in 90%+ of the valley since we are a flat city.
There are some exceptions. I live right behind Black mountain and get the Fox and NBC OTA HD channels fine (since they are on that mountain), but the ABC and CBS towers are blocked due to how my house sits down in the ground with a 30 foot wall right behind it blocking that signal.
Overall though, a basic OTA antenna will give you your HD locals in vegas crystal clear.