Oh, yikes! I have flown a bunch with my daughter (now 20 months) from Maryland to Texas in the past year but that's just 3 and 1/2 hours. I definitely agree with the suggestions to bring snacks--especially finger foods she can feed herself. I usually take things like blueberries, cubed cheese, goldfish crackers--they are fun AND time consuming to eat. I also agree with having a stock of toys she hasn't seen before. And try to bring them out one at a time over the course of the flight. That way, when she's bored with the first one--tada!--another new toy! Although, at 17 months she may catch on and start looking for where they are all coming from. Don't forget to let her choose at least one of her favorite toys or stuffed animals to bring, but not too many to keep track of. Nothing would make a good trip go bad like losing her very favorite animal friend on the plane right at the start. Maybe give that favorite friend a pretty new ribbon so you can tie it right to your bag. And last but not least, I'd say fully half my time on the plane is spent singing, reciting poetry and stories or playing games like pat-a-cake or "here is the beehive." No doubt you you know many already but if you can, learn some new ones! Good luck!