Traveling with kids SUCKS! It's horrible. I absolutely want to take adventures and see the world with my child, but let me be honest by saying that I'm literally praying daily for someone to invent teleportation or the "beam me up" situation from the Star Trek. 
Before I had a child I would say I was an expert traveler, I had packing down to a science, and the ability to travel anywhere at anytime. Now? Oh, how the game has changed my friend. As a person living with anxiety I really don't enjoy the traveling with my kid in tow. It freaks me out! I need lots of time to prepare, pack, repack, panic, and repack again. That usually helps me control the anxiety, so needless to say, I'm pretty good at it. Here's what we so to get through it. ***Note this is for ONE parent flying with ONE child.***
His Carry On: (Boy 3 1/2 years old): Pick a backpack that has plenty of room but that your little one can wear or even better a rolling back pack like the ones from Pottery Barn Kids that they can pull around behind them. In quart size ziplock bags separate the small toys, crayons, etc so that you can not only see them but feel them while you're searching thru their bag for them because they just can't (ugh.) Grab a few brand new Grab and Go fun packs from the Target dollar section or the Dollar Store. Get one new decent sized toy that kiddo has never seen before but really likes (i,e. a Spider-Man or Barbie, or an Imaginext) this way they have a surprise that will keep them preoccupied for part of the plane ride. On this trip we're trying a new Disney Star Wars kinetic sand playset...it may be a disaster, but he loves them and it will keep him entertained (wish me luck.) 
I swear by the iPad mini, but make sure you have enough memory to download a new movie and maybe a few episodes of their favorite show, just in case there isn't any wifi. Other Apps to consider are VUDU, Disney Anywhere, Netflix and YouTube Kids for wifi hotspots or even use your phone as a hotspot for driving. Snacks: just a few so that they can grab it themselves. I pack 1 Pirates Booty, 1 Veggie Stick, 1 Annie's fruit snack, and one small pack of cookies or graham crackers...but here's the thing if you run out of room just grab some snacks after you get through security. We usually find hummus packs, yogurt, a bagel, or pick up a smoothie at Starbucks. Pack a hoodie, an empty water bottle, some toddler flushable wipes, a spare pair of underwear and a wet bag or gallon size ziplock bag for any accidents that could occur. Don't forget their blanket or favorite stuffed animal for comfort.
My Carry On: I carry a pretty big (but very chic) back pack. I don't do the tote bags because they tip over, can be reached inside of and they pull one shoulder down or slip off and just make your life a little more unbearable. A backpack makes your hands free to hold onto little ones and a rolling suitcase. Keep liquids to a minimum (if any at all) and contained to a quart size ziplock or clear makeup bag. I pack a few daily wear contacts, mascara in travel size, hand sanitizer spray, lip balm and a good tinted CC cream (you can buy anything at your destination that you may need beyond the bare essentials.) I highly suggest skipping the laptop computer if you can and investing in a good tablet that can replace it while you're traveling. I love my iPad Pro and found it at a good price at Costco! You won't have to unpack the iPad's at security so that totally rules. Grab a comfortable, light and versatile cardigan for the air conditioning and a bonus is that it can double as a blanket. Lululemon or Three Dots make great ones. I pack a compact cross-body bag in my carry on. When I need it on my trip it's there but one less bag to sling around my neck at the airport. You can even store your wallet, keys, and sunglasses in it and ready for when you get to the hotel. All you need accessible for travel is your photo ID, boarding pass (which you can put on your phone now), cash and your phone. Hello! That's why I suggest a backpack plenty of little pockets for that crap. Remember to bring a snack for yourself, a refillable water bottle, toothbrush, antibacterial wipes, facial wipes (please don't confuse the two...ouch) and your phone charger. In fact, most of the time I only carry the USB cord to save room because you can plug it into a hotel TV or charging station at the airport. Most places have joined the tech revolution and have USB ports for charging now. We only need one cord for all of our devises. A good pair of ear buds or headphones just in case you can manage to catch a movie or listen to your tunes if kiddo falls asleep is a bonus.
What we pack in our Carry On Size Suitcase: Basics and favorites. For a 4 day trip we need to keep it simple. Anything longer try to see if laundry is available. I only fly with a carry on suitcase. I almost NEVER check a bag. I can't stand waiting for it to get off of the flight and such, and for us that has added an extra hour stuck in the airport and not on our way to the fun stuff.
For my little dude: I pack sunglasses, a baseball cap, 4 pairs undies, 3 t-shirts, one collard shirt, 2 shorts, 1 pant, 1 pair of pjs, one swim outfit, 2 socks, 1 pair of sneakers, 1 pair flip-flops or crocs. (Remember the hoodie in the carry on.) Roll each outfit together including undies. Stick socks into shoes. Anything over that is too much probably. Lay it all out and see if you can edit or combine outfits to make even more room. Here's where you can get them involved....have them pick out the clothes they want to wear. My son hates to wear a collard shirt or anything dressy so I have him help me choose his outfits. I have a higher success rate when his opinion has been factored in.
For me: I can get away with dresses for day or night and simple sandals. For a 4 day trip I do denim cutoff shorts and 2 cotton tank tops, cotton sundress, simple black dress that can be worn day or night, white jeans with a grey or black cotton t-shirt, maxi shirt and white tank top and one basic black bathing suit. (Remember you have a cardigan in your carry on bag for layering.) Do your self a favor and just leave the crazy big platforms and whack ass fancy heels at home, girl. You won't want to be burdened with them in your bag. Simple black sandals, comfortable flip-flops, one pair of comfy pjs, however much underwear you feel you need, and 2 bras should be sufficient. You can wear your sneakers to travel in.
Consider shipping: Diapers, liquids, bulky items and extra clothes can be shipped to Grandma's, but you can also check hotel policy and for longer trips this is super simple and easy to do and just makes dealing with checked bags a thing of the past. Hallelujah!
What we're wearing to fly: Gone are the days of dressing to the tens for airline flights. Boo can wear his favorite t-shirt, comfortable cotton shorts (with pockets if you can,) crocs and a baseball cap. I always travel in black leggings, cotton tunic style t-shirt, 'no-show' socks and Adidas sneakers (preferable black and white because they go with all of my other clothes.) I wear a sports bra to travel in just in case I get the ol' frisk and fondle by the TSA agents. A baseball cap always is helpful so that you don't ruin your blowout by pulling your hair up and wasting that time an energy.
Airport Tips: Buy snacks and fill water bottles after you get through security checks. Make sure you are early for flight times...and by early I mean like an hour or more kind of early. You have no idea how long the lines can be, who will need to pee or poop (which with a newly potty trained kid can take some time) and it gives you plenty of time to make sure you can check in at the gate and let them know your needs to pre-board. A few times I have been lucky enough to upgrade seats to first class or business class on the cheap so look out for these options. Trust me, they call it first class for a reason. I don't like traveling with a stroller or car seat. It's just as easy to rent if you need to. Try finding a car service that supplies the seat. You'll have to buckle it in but that's old hat for a seasoned parent. Less is more here, people. I have been known to buy a cheap umbrella stroller at Rite Aide or Target in desperate times, but I prefer not to relive those. Once you've been seated on the plane make iPads readily available along with water bottles and blankies. Sometimes the pilot will let the kids see the cockpit which is pretty cool and totally take the flight attendants up in the little wing pins...cause that's about all that is free on an airplane now. Also, if you can allow your little one to sit in the window seat you'll be happy to have that entertainment but if not the middle seat will do and if the person next to you is annoyed offer to buy them a drink. This is real life and in real life kids travel so we all have to deal with it. They can be nice or go to sleep.
Many trips will be taken, many people will be annoyed by kids on an airplane...even in a train or on a boat...it all sucks. But for us it's about memories. Try to be prepared, try to keep your wits about you, try not to over pack or over stress (like I have a tendency to do) and remember to have fun. As much as we hate the travel grind the kids can't help who or how they are and most of the time they're more well-behaved than the adults.
Good luck and ALL Love,
W and B
