I read some of the other responses -- Please don't medicate! Especially with all the new evidence about the downside to medicating children under 2 years old!
I don't have any great advice except pack your patience. We flew with my youngest when she was 11 months old. Not nearly as long a flight (only to NJ, about 3 1/2 hours), but we did have connecting flights on the way home, w/delays. It wasn't as bad as I was anticipating. She behaved quite well. Obviously, at that age, a child's attention span isn't the greatest, but we brought along her favorite toys and books. Do you let your little one watch TV yet? If so, then a portable DVD player is a must! My daughter loves Sesame Street and Raffi, so those DVDs helped to keep her occupied (and I didn't feel too guilty because I think Sesame Street is great and my older daughters' grew up on it and both are great learners who would rather read than watch TV). She napped, but not as well as she usually does in her crib. This actually helped with the time change, because she was tired and was willing to go to sleep early (since NJ is an hour later). The toughest part is if you need to change a diaper because there is no space unless the flight isn't full and you can use an empty seat. Otherwise, kick your husband out of his seat for a few minutes (assuming he is sitting next to you) so you have a little more diaper/clothes changing space. There is also the issue with cabin pressure changes when you take off and land. My daughter did very well. When we were coming down, she kept brushing at her ears but it never bothered her to the point where she cried. The general advice to deal with cabin pressure changes to to have your little one drink his bottle as you are ascending/decending, but my little one wasn't interested.
We also drove to NJ (a full 24 hours) when she was just 6 months old, and again, it wasn't too bad. I think you will be surprised that traveling with your little one with go smoother than you are anticipating!