We are not shy about lugging our kids on a plane to see the relatives. Thank God for the mileage we have built up over the years because we have a couple of trips still left in us. Packing, however, is still a pain, no matter how many times you do it. Only through trial and error did we figure out the things we really REALLY needed to pack.
The car seat bag can do double duty. One of the first things we bought before our first trip was a $20 bag for Ethan's car seat. We weren't so sure about the purchase at the time but it is by far the BEST $20 we have ever, ever spent. Now I know that the airline will sometimes give you a heavy duty plastic bag to protect your car seat, but how many times have you watched a seat go by on the baggage carousel looking like it had been on a trek through the Andes rather than in the luggage compartment? The bag also serves as a place to pack extras for us. We tuck the trip's allotment of diapers in the seat along with the heavy baby wipes (since we are cheap and buy everything in large quantities) a pair of my husbands bulky, heavy boots that he absolutely HAS TO HAVE on vacation and even our heavy coats if our destination is colder than our place of origin. These items are bulky and while you can save space by just buying diapers at your destination, who wants to pay a lot more for them? The car seat doesn't count as one of your allotted bags usually, so it's kind of a freebee. But the best thing is, on the way home when almost all the diapers are gone, we cram a bag of dirty clothes into the car seat bag along with the seat. Ethan's seat has weathered every single trip without even a smudge of dirt.
Take the time to plan out what clothes to pack for your kids. You are probably thinking, who doesn't do this? Well, on occasion, I have been known to pack everything shy of the kitchen sink because I waited too long and then got rushed at the end. Keep in mind that if you are going to Nana and Grandpa's house, you will most likely be able to do laundry. So for that 3 month old baby that goes through 9 outfits a day, you just might need to pack for 3 or more days. I know their clothes are little and there is a temptation to pack every single clean article of clothing, but remember that you have to lug that bag around. Surprise trip to see the snow 45 minutes away that you didn't anticipate? Those jackets are a great early Christmas present from Grandpa this year.
Pack a separate carry-on "diaper" bag for your kids, and then tuck away a few extras in your carry-on bag. The diaper-per-hour trick is tried and true. I always try to skimp and then am so thankful for my husband who has managed to tuck an extra couple of diapers (and an extra baby outfit) around his laptop to keep it safe. No matter what your child's pattern of diaper usage, throw it all out the window come travel day. When Ethan was an infant, he always used twice as many diapers on travel day than he did any other day. It was crazy. That and every single diaper always leaked. Be sure to save that special outfit you wanted Nana to see for either the last change before landing or the change that happens right before you go to baggage claim to pick up your luggage. It greatly reduces the odds of getting ruined before the grandparents even see it.
Make the room to pack an extra outfit in the carry on for Mom and Dad. When Ethan was an infant, it only took us 4 trips to realize that at least one of us was wearing poop and the other was smelling like throw-up when we finally got off the plane. If you have an infant and the plane ride is longer than an hour, your chances are 10 to 1 that this will happen. For anyone who has taken a "bath" in the lav on a plane, you know that nothing really beats getting out of those nasty clothes and into something fresh. At a minimum, take along an extra shirt for yourself. No matter how many burp clothes you have, your baby can always seem to find the spot on your that is not covered.
Don't pack your bags too full. Nana had a few "surprises" for the boys that were beyond what she had already forewarned us. After one too many trips to the store to buy a duffle bag to cart stuff home from a vacation, we have learned to just leave some extra room in the bags. There is nothing worse than realizing that your bags are too full and you haven't even finished packing back up to come home.
These tips have worked for us (and saved us) many times. Hope they can spark some good ideas for you on how to make your plane ride with kids as stress-free as possible. Please share what your tips are?