Request to sit at the front (not first class) of the section so the kids can play on the floor. You have to sacrifice the space for your luggage under the seat in front of you but it’s worth it for them to crawl around – and you get to stretch your legs.
Give the kids the window seat.
Let them have special snacks.
Take them on walks down the aisles occasionally (and let them jump around and get their wiggles out near the rest room area).
Don’t forget to bring a variety of quiet toys (you gotta mix it up because they get bored fast).