Hi K.,
First, let me apologize for the novel, but hopefully you'll find some useful things in here that you can use to keep you from repeating other's mistakes. I think the biggest thing you can do is to BUY HER A SEAT AND HAVE HER SIT IN HER CAR SEAT (make sure that it's an FAA-approved one and one that will fit on your plane).
My husband and I flew with our little boy when he was 1 1/2 years old and it was SUCH a difference from when we flew with him at 5 months old (think nightmare-, versus dream-baby!!! :-).
By 1 1/2, he was soooo independent and no longer wanted to sit on our laps and be held all of the time (in fact, his favorite word while holding him was "down", repeated several hundred times, of course!!). So, our big mistake on that trip was bringing him on as a LAP baby!! (duh! it all seems so clear NOW!). Anyway, we vowed that the next time we traveled with him, he'd have his own seat!!
So, when we traveled one more time with him back in September, we bought him his own seat (we had to anyway, since he was almost 2 1/2) and strapped him into his carseat and it was soooo much better. Since he was familiar with the seat, he knew that he had to stay buckled, which is MUCH safer than having him walk around.
We also brought lots of his favorite snacks (cheerios, raisins, whole grain goldfish, carrots, his favorite crackers with some cheese) and two sippy cups with milk and water (security will let you come through with bottles / sippy cups).
For ascent and descent, the stronger the chewing or sucking that is required to eat/drink those snacks, the better!! So, we used the carrots for this reason and also brought some dum-dums lollipops (he looked forward to the "treat"), along with using sippy cups that required stronger suction, to really get the jaw working and help clear he ears during ascent and descent. (I sometimes have problems with my ears clearing, so I was prepared)
We also brought some things to color, a few of his favorite toys/books, and some completely new toys / books (and stickers!) that he'd never seen before---all to maximize the level of distraction. Whenever he would get a little cranky, we'd unveil a new toy...he loved playing with those new toys!!
We also packed a change of clothes (or two) for any mishaps, of course...
A couple of additional tips:
- Sit at the back of the plane, so that the noise level is highest (the white noise can sometimes help them sleep). This last time we sat right behind the wing and Connor loved to see the engines and the flaps moving on the wings (he's fascinated by airplanes)
- If you're taking your carseat, place it on one of those carseat carriers (wheels), so that your 2-year old can ride through the airport (make it fun). This means 2 less things to carry---the carseat and your toddler when she gets tired. I think the brand we used was GoGo Kidz or something like that.
- Get a removable tray that can give your toddler a flat surface to color on, play on, snack on. Unfortunately, the seat-back tray in front of them will not come down completely, thanks to their car seat. Here's what we bought: http://www.amazon.com/Star-Kids-Snack-Play-Travel/dp/B000...
It's a bit flimsy for some types of play, but it's that way so that it will bring no harm during turbulence, since it collapses on impact. It's also easy to pull on and off your child or her seat, so if she can't play on it, or gets tired of it, you can take it off.
Finally, I just have to say this: I disagree strongly with the advice re: having your 2-year old chew gum (waaay too early) or giving them Benadryl. I had also heard of the Benadryl thing from other parents when we were first going to travel with our son, so I asked my pediatrician. He (and his nurse) looked at me like I was crazy to ask whether I should drug my child to travel with him! Needless to say, I never did it and we survived just fine.
Yes, it will be challenging, but that's no reason to give them a drug inappropriately (Benadryl is supposed to be used to counter allergic reactions, not knock out kids)!!! sorry for the soapbox, but this is why we keep having infant/toddler medications pulled from the shelves...because of parents mis-using them (It makes me angry that responsible parents are also being punished by not having medicines (like cold meds /decongestants) available to them for their correct use!!)
I apologize for the last-minute rant :-) and I really hope this helps you!
D.