I'm flying from AMS-JFK in a few days (it's a return leg) and was thinking of paying to upgrade my seat to business. I was wondering what the best way is of securing a relatively low-cost upgrade? Many years ago when I flew from AMS I remember they offered a ~260 EUR upgrade when I checked the kiosk at the airport. Is the best way of getting a similarly-priced upgrade to go through the kiosk, to check in online the night before, or just ask at the counter at the airport? Thanks in advance for the help!