Will be flying Singapore Air from to LHR, and looking at catching a flight from LHR to either AMS or CDG to overnight. Then catch a flight to the US, most likely JFK. I would do this option due to saving several hundred vs catching a flight with connections from LHR. Looking at flying KLM or AF in premium comfort, and possibly even in the J cabin. Can anyone tell me the difference in products comparing the two in each cabin class. Thank you