[jazzyjackson]

There is one airline that flies all business class. An A321Neo with 76 lie-flat seats, NYC to Paris/Nice/Milan. Random date selection yields $2700 one-way New York to Paris.

https://www.lacompagnie.com/en/about/services

[ivandenysov]

British Airways operated a similar flight between 2009 and 2020: an A318 between LON and NYC with 32 lie-flat seats

https://en.wikipedia.org/wiki/Club_World_London_City