Our daughter is 3 1/2 now and between severl trip and connecting flights, etc. has flown on 10 separate flights. She is generally very good, and in all that time she cried/whined for about 3 minuites. The best thing is to BE PREPARED for anything. You're here asking questions, so obviously you already know that!
These are the things I always do, some of which were previously stated:
1. I bring as many "new" things as I can, but don't forget a few "familiar" itesm from home. WHY: My daughter (and most kids I think) will play with something new far longer than something that's they've already seen a million times. But 1 or 2 "familiar" items should be thrown in, in-case they seen uncomfartable with the entire process.
2. I pack a "snack pack." A gallon-size ziploc or plastic pouch that a toy came. WHY:I find that my daughter is better when she has
options to choose from. It's all about PREVENTING the whining "I don't want THAT!" even if it is their favorite snack. Showing her a clear bag with several mini-bags of healthier and/or familiar snacks as well as a few special "treats" is the best way to go. She'll burn up time looking at the options and choosing too!
3. I always pack fruit snacks and those tiny dum-dum lollipops and give to her for take-off and landing. She's never once complained about her ear pressure or the popping.
4. I try to avoid things with several parts and/or round objects (i.e. crayons). WHY: Crayons and markers especially, can easily roll off the tray and the last thing I want is my daughter whining about "the green one" and having to bother people in front or behind us to move their bag and get the marker time and time again.
5. I love, however, Color Wonder products, and the knock-off counterparts. but particularly ones that have "games" and "hidden objects." WHY: The ones with games and hidden objects last far longer than coloring a picture over and over again, plus they really only require ONE marker (see tip #4!). I recently found a Disney Princess activity bok at Wal-Mart for under $4 in a special area in the toy dept. It's thick and has many pages of activitys such as an entire page of blank circles, but the object is to use the special marker (just like a Color Wonder marker) to find the objects hidden within them. Pluse there are "coloring" pages where you just color the princess picture and the different colors are alreday on the page, you just use ONE marker. (Sort of like those water-color books).
6. I always grab an egg of Silly-putty. WHY: It's not all that messy if you keep an eye on it and can be formed into shapes and also pick-up images off of paper, by pressing it over a page in a coloring book, etc.
7. A mini Magna-Doodle. WHY: Pretty self-explanatory. It just keeps her occupied. Kids love to see their names written, draw silly faces, make patterns, etc.
8. Blank paper and stickers. WHY: My daughter just LOVES stickers. I go to the dollar store, Dollar General, family Dollar, etc. and pick up cheap packs, usually with a theme. Right now we have all Disney characters. Previous trips we've had fish and sea shells, cars, etc.
9. I go on Highlights' website and print out a bunch of their their hidden pictures pages, fold in 4 and put a stack in a ziploc bag. WHY: My daughter loves to find hiddne pictures and it take s a lot of quite time whiloe searching. They have all skill levels to chose from. Pack a special pen, marker or crayon for these!
10. A blanket and a small pillow.
11. Clothes. An entire extra outfit just-in-case, including a sweatshirt. I dress my daughter in layers, becasue you never know the temperature/air changes. It's easier to throw on a sweatshirt, etc. than it is to change an entire outfit! We often travel in early morning or late evening, so I either dress her in pajamas and will change clothes in the airport, or vice versa.
12. Extra diapers, more then you think you'll need. You never know if you'll be delayed, etc.
13. Plenty of Wipes! Obvisouly, can be used for diaper changes, as well as hand cleaning, tray wiping, etc.
14. A key-ring mini-bottle of hand sanitizer, attached to our backpack.
15. A sippy cup. (Airline regulations have changed, you can only take 3oz. of a liquid thru security. An empty sippy cup is fine, we just buy juice at a shop before boarding and fill with water from a drinking fountain)
16. Books. But only the thin paper-type. Heavy hardcover ones will only be, well... be heavy!
17. A catalog (like Pottery Barn kids) than I can tolerate looking at, but my daughter will enjoy pointing out babies, colors, objects, etc. I usually save a new one from the mail and not look at it until the flight.
18. On all our trips we've never had a portable DVD player. We never really missed it, but for our upcoming trip I did buy one and packed a few DVD's together in one case.
General tips:
1. For carry-on luggage, I always have just have 2 items. One is a wheelie-bag with all the toys, snacks, sippt cup, blanket, etc. that will stay down on the floor and has all the things we will need during the flight. It also has a habdle to be carried. I used a photo key-chain and put pictures on my daughter in it, to occupy her while waiting in line for security. the othe item is a backpack. I can't emphasize this enough! I learned the hard way that I physically cannot carry a child and 2 bags thru an airport, while having to take off my shoes for security, hand boarding passes, etc. A backpack I don't need extra hands for!
2. I keep the daipers, some of the wipes and the change of clothes in the backpack. It's already on my back when I'm headed for the restroom in an airport, and I don't need to contaminate the "toy" wheelie bag.
3. EVERYTHING I chose to pack is as lightweight as possible. I consider this when choosing clothing, books, snacks, etc.
4. Check FAA guidelines BEFORE you pack! They're constantly changing their security rules. (You now need any liquids and in a quart-size ziploc bag, etc. and can't take drinks on, etc.) You should know these rules before you go and make it easier on yourself!
5. Remember you will likely have to remove your shoes to go through security. We all wear slide-ons (even with socks) so we can be both comfortable on the flight and get thru security easier. (Also learned that when we were late for a flight and had to RUN throu security and carry our sneakers in hand becase we didn't have time to sit down and tie them!)
6. Pack and "lovey" items of your children's AWAY in a bag as early as you can. My daughter has a cherished stuffed bunny that goes everywhere with her. Our very first flight she was holding it when we hit security. We had to pry it form her clenched hands and watch it go thru the VERY SLOW conveyor belt. It was traumatic for her. We now hide it in a bag when she's not looking, like while getting our boarding passes or even in the car.
7. Ive never bothered with a stroller or car seat. In my eyes, it was never worth the hastle. It works for others though, just not for us. Having my hands free and less items to carry and put together/take was better for us! Alos, on the plane, whene she slept, i (personally) thought it would be more comfortable to lean against us with a pillow and not be hindered by a hard car seat.
That's all I can think of right now, hope it helps. Have a great trip!
My 2 yr old will be in a car seat and I heard you can not put the tray down when using a car seat. How do you keep them busy for hours? There are only a certain amount of snacks I can give her 
that will get old fast.
