I paid $639 to upgrade to Delta's Premium Select cabin on a 15-hour flight. It was a great alternative to business class.

Source: Business Insider

I paid $639 to upgrade to Delta's Premium Select cabin on my flight from Atlanta to Seoul. Kimanzi ConstableI paid $639 to upgrade to Delta's Premium Select cabin on a 15-hour flight. The seats felt noticeably larger and more comfortable than those in economy.