Extra clothes for everyone, not just baby.
Food in the pouches,,,we did BLW and never used purees but those things are genius for travel.
Our daughter used to sleep through all the flights...now at 13 months she has started staying awake through all or most of the flight so it's all about entertaining the baby. Some toys, windows, other people, anything from the seat back pouch to keep them busy.
Oh, and as you get off ask if baby can sit in cockpit. Our last flight they let my 13month old sit in the pilots seat (with co-pilot in the other seat) and they let her play with the buttons! Made for awesome pictures. My husband got to go talk with the pilot which he loved too!