I traveled from California to Chicago by myself when my daughter was 9 months - no red eye flight, and one stop (and it was her first flight).
1) Make sure you have enough toys, liquids, snacks, diapers and wipes (those Gerber puffs are awesome).
2) Take the very minimum you need to have with you. It's amazing how little you can get away with when faced with carrying it all yourself.
3) I didn't use a car seat on the plane, so that was not an issue for us. I used this for safety: http://www.babyuniverse.com/pro/baby/26873/FlightVestTrav... It's a Baby B Air - found a great deal on Ebay. You might always want to check the Craigslist in your area.
4) I bought a cheapo umbrella stroller to get around the airports and such. You can take it right up to the airport entrance and they will check it there for you. I bought a cheap one because if anything happened to it, I wouldn't care (it was $10).
5) Last but not least, fear not. I was floored, amazed, and thankful for all the people who didn't hesitate to help me when they saw me struggle at all. One of my seat mates even told a soap start he couldn't use my overhead bin because I needed it for the baby (I was still settling in). Ok, he probably didn't know the guy was a soap star, but I did! LOL
Sounds like your little one is already a good traveler - hopefully he will be again! My daughter did great and entertained quite a few people on our travels (she didn't sleep a wink).
I think the biggest thing is to make sure your son is as comfortable and happy as you can so he doesn't bother other passengers. They are a lot more helpful that way. LOL
Good luck and have a great trip!