In July and August 2019, I flew between Amsterdam and Brisbane return on Korean Airlines. This was the second time we had flown on Korean, the year before we also travelled with them, this time including Auckland in our route, and staying overnight in a local hotel.
This time I was on my own with my girls, aged 10 & 12 and we had about 4 hours in one direction and 7 hours in the other direction at the airport. We were really impressed with Incheon! They have a nap zone, free showers, and various activities and entertainment.