D.S.
Get there in plenty of time so you are not feeling pressured and can enjoy showing her the sites. Know that you'll probably have to take her out of her backpack or stroller. I agree about empty sippy cup through security. I think they are supposed to allow bottles of milk, but it doesn't seem like something to fight about on the day of the trip. My son has flown numerous times, starting at 6 weeks, and has never had ear pressure problems. I nursed him and now he drinks from the sippy cup. I didn't prepare for the taxi time the first time we flew and he was asleep by takeoff. I tried to get him to nurse during assent, but not doing it much didn't seem to bother his ears. Bring LOTS and LOTS of diapers and changes of clothing. Even after we arrived in KS, I had to change him several times with loose stools. (And I've read about lots of other kids in the same boat. Probably not as much of an issue as they get into toddler hood, but doesn't hurt to be prepared.) Try and enjoy it!