Frontier and Spirit have round-trip flights from Denver (DEN) to Las Vegas, Detroit, or Fort Lauderdale (LAS, DTW, FLL) for $35-$50, NONSTOP. Flights January to March. Extended weekends available. Most flights are depart on Tuesdays, Wednesdays, or Saturdays. Origin/Destination reversible.
Note: Fares do not include a free carry-on bag. Only a small personal item, like a Jansport City Scout backpack is free. You can avoid paying for seat selection if you accept the randomly assigned seat prior to boarding.
Note: Seats only have 28-inches of pitch; 2-to-3 inches less space than most other airlines.