Airlines frequently update their premium classes. The long lead-time schedules for updates and variations between aircraft types often make it difficult for passengers to know if they will be flying in a comfortable, modern seat for their class. US airlines are planning a number of major upgrades in near future.
For example, American Airlines will be introducing lie-flat First and Business Class seats in the 10 new Boeing 777-300ER aircraft it will receive beginning at the end of January. The airline will update its old 777-200 aircraft as well as half of its 767-300ER with better seats starting in 2014 and also introduce many new aircraft including the Boeing 787 Dreamliners.
A comprehensive guide for the upgrade schedules of four major US airlines – AA, United, Delta and US Airways – can be found here:
Maximizing the Newest Business and First Class Products on US Airlines