Change of Clothes
Make your seat feel a little more like your bed and ease up on jet lag by changing into comfortable clothes to sleep in (up to you if they’re going to be pajamas). This will also prove handy in the unlikely occasion that you lose your luggage, or for flights with long layovers.
Copies of Your Travel Documents
In the spirit of being handy, keep copies of reservations, tickets, travel insurance policies, and the biometric page of your passport (and visa, if applicable) in a sleeve or envelope in your luggage. Chances are, you won’t need them, but it’s always better safe than sorry, especially if we’re talking about a few sheets of paper.