ANOTHER place to look is an airlines called Allegent Airlines which is a discount airlines (they charge for every bag). They have tons of inexpensive non-stop flights from some of the smaller airports. We use Allegent from Rapid City to get to Vegas, and other places that are more obscure (Like Rapid is).
https://www.allegiantair.com/en/flights-to-las-vegas
Fly direct from Rapid, Des Moines, Appleton/Green bay, Bellingham, Cedar Rapids, Peoria, Sious Falls, Fargo, Knoxville, Indianapolis, Minot, Omaha, Flint, Grand Forks AND MORE, all for $38-$85 each way.