Try JetBlue Airways - it's a very popular and trendy airline that offers low-cost tickets and very comfortable rides. They do e-ticketing and everything can be easily done online (including picking your own seat). The flight will take you from LAS Las Vegas to JFK New York and it's around US$160-200 one-way. I've had really good experiences with JetBlue - hassle-free, fast check-in, and comfortable. Website: www.jetblue.com