I will say that the airlines do make travelling with children as easy as they can. What I am going to share is my personal experience and may or may not be what you experience at the airport. None-the-less these are things that I wish someone would have told me before I flew!
You can take as much in the way of solid food as you want so load up on goldfish and any other solid food snacks that you want.
You cannot take liquids unless you have a baby who is breastfeeding or getting formula. If your baby is less than a year old then the TSA are very nice and allow you to take whatever the baby needs in the way of breast milk, formula and baby food.
You can transport a breast pump but not breast milk unless the baby is present when you are traveling.
Don’t forget to take the car seats that you will need when you arrive at your destination. I have a special bag to put them in and it has been awesome. The airlines are not supposed to charge you for checking-in car seats which is something I wish I knew when we flew out of Greensboro on Delta in October. The person checking us in knew that they were car seats and sadly she charged us the fee anyway. On our way back at the curbside check-in in Dallas the man who worked with us made sure that we did not get charged.
Take an unbrella stroller! It is easy to stowe on board an airplane and well worth having it!
Scented dirty diaper bags are a life saver if you are staying in close quarters with other people and have a baby in diapers.
This portable pack-n-play type “Phil and Teds” has really been very useful for us over the years since it folds up much smaller than the other pack-n- plays and weighs next to nothing.
Buy one of these fold-up toilet seats and put it in your carry-on bag. You will be glad you did if you have a little one who is independent in toileting!
I also found a nice article containing tips for what to take for kids to snack on while you travel so you may want to check this blog out. There is a lot of other helpful information about flying with kids on this site as well.
You are planning to drive instead of fly? If that is the case some will tell you to make sure there is a way for the kiddos to watch some TV. If your car does not have a DVD player in it you can always bring a laptop and slide a movie into it. Personally, I am old fashioned and still make my kids play games and talk to me. When that gets old they LOVE their Leap Frog Tag Readers which I can't recommend highly enough. Will say though that if you have more than one child and each one has their own reader I would recommend headphones. I also have a friend, Rebecca Subbiah, who has written "101 Tips For Traveling With Children" which is a cute little handbook that you can get as an ebook for around 3 bucks. It is money well spent.
The last thing I will say is relax! The lines will be long, there will be a lot of people and conditions will be right to make for a stressful time but keep your cool. Your family will thank you!