I'm a huge fan of Virgin America. I think the airline makes a lot of sense for infrequent travelers. You're not competing with status-holding members, and you get Wi-Fi, in-seat entertainment, and some of the best food / drink options in coach. I blogged about a flight I had in Main Cabin Select some time ago. So... how does it work?
Elite qualification is based on "status points," and the qualification levels are as follows:
Silver: 20,000 ...

