I think you have lots of good suggestions here. I have a 19 month old girl and she has flown probabl close to 19 times in her life. Make sure you talk about what you're going to be doing for a few days before hand. I always talk to Lucy about going in the plane the week ahead of time and we'll look for planes in the sky and talk about how we'll go on a plane to see...(whoever we're going to see that time). We do enjoy when she gets her own seat...which your son will since he's 2. I have a special backpack I use and I put her favorite books and some toys in it. I paid $7 for a toy airplane that looks like the airplane we go on...we fly southwest usually, so I picked up a southwest airplane for her to fly while we're on the plane.
Another big hit is Color Wonder magic markers by Crayola. They color on the page only and its a special treat for the plane to use markers...plus no mess! Bring lots of snacks and special treats...and be prepared to be busy the whole plane ride...travel with a child is always exhausting!!