Hi P.,
You already have some great advice, just wanted to add some ideas that I used with my girls when they were about htat age, we travel every year to Argentina (day and night flight) so flying to Denver.....easy as cake!:)
Things that helped me a lot: chewable fruit snacks so your baby can chew while landing and whenever you feel your ears tight or plug. I am not shure if it is because they are chewing or because they like the "candy" but it helps!
Other thing, baloons! Many size and colors, water baloons the little ones, you can put some anywhere! They are little and don't take any space and you can inflate them any time you need them (make sure you take enough in case they pop:)
Lollipops, they are great for emergencies!
A new toy, one that is not big but that will keep your child entertained just because he has never seen it before (you know how it is).
You can also get favors for birthdays, they are very inexpensive and small enough, like, balls with lights, light sticks if you travel at night, musical instruments (the tiny plastic ones for parties ar not noisy) A couple of your favorite books to read to him over and over....
Something to doodle on? Once I got a pencil that has for colors in the lead and my little one spent a long time trying to figure it out.
My kids always enjoyed the trips, and even slept wondeful at night. Don't forget the stroller for any waiting at the airport, he might even take a nap while waiting.
And most important of all, relax! He can sense if you are nervous and that won't help.
Have a great trip and enjoy your stay with family.
Mariana Abadie
www.MyKidsFirst.com