Hi Carolyn,
I have 15 month old and we are also going to travel for Christmas, we did before in summer and it is 8 hours trip, so i have some experiences. If she doesn't suck on bottle, than give a pacifier or just some rubber toy or food (even the sips from sippy cup should help), the trick is to make her swallow and reduce the pressure in her ears that way. We always get the seats in the first row (our airlines actually have it even like a must have for kids under 2) it is right in front of the wall (behind the first class), so you have much more space and most importantly you'll get the bassinet which they hook on the wall, so your baby can sleep or sit and play in her own area (not that it would be that big, but it was huge help for us, that we didn't have to hold him whole time and he slept in there very comfortably) i don't know how you feel about plane blankets, i just brought everything, his blanket and sheets, so he didn't have to suck or even touch the bassinet, not that it would be that dirty, but i am just picky and even thought that he might feel also better to be with his own stuff which smell familiar and are his. I am going to bring him this time also couple of books, he loves them and they make him occupied for long time. Don't forget plenty of diapers (one of the moms who i know thought that she would buy them on the airport, and than was shocked that they didn't have them and her baby girl peed on her and it just wasn't fun, i wouldn't really expect diapers on the airport but obviously some people are...so from this my other advise is, whatever you want to have bring your own!) Another thing..i don't know what stroller you have, but we always check it at the plane, that way, your baby could be the whole time comfortable in the stroller and you don't have to carry her around with your carry-ons and other stuff - huge help also. We always wrap it and tape it before we will give it to them, that way it doesn't get dirty. Some strollers have their own bags but i heard that they are too big and because of that you actually have to check it with your luggages - so not really helpful. And thats probably all what just pop in my head, if i will think about something else, i'll let you know! Have a good and safe trip and lots of fun.
L.