Please don't give him Benedryl unless you have given it several times before. A huge percentage of children (mine and several others I know) have the adverse reaction - meaning it hypes them up beyond control. I can't imagine anything worse on a plane.
Whatever he will suck on is best - bottle, paci, whatever. Also - with his age, I'm sure you will start getting pressure to take away his bottle and paci at 12 months. Do not attempt to do this until after the trip is long past. I also wouldn't switch to whole milk anytime soon - it will be easier for you to take powdered formula (if you use formula) to a foreign country. Most countries have different milk than we do, and it will upset his system. Also - keep him on the same schedule he is on here - don't try to adjust him to the time change.
Other than that - just have fun and take lots of pictures. I have traveled a lot with babies/small children and it always turns out great. Being prepared is the best plan.