I do not travel very often, and am unfamiliar with the current prices for upgrades from Coach on various airlines. I'm planning a trip from DC to Arizona, and am curious to know whether it is possible to purchase a Coach seat, and then purchase an upgrade a couple of days before departure (if seats are available), since this is generally cheaper than buying a first class seat. Could you please tell me about the upgrade methods that are available to non-elite/platinum/etc. frequent flyer members. Thanks in advance.