Flying with 2Yo

Get the gogokidz travel mate for sure! Used mine over and over and loved it! Don't bother bringing juice, you will have to purchase it after security, and you are always able to opt out of the scanner, but be prepared for a pat down. Some tsa agents are great, some are awful... Just take a deep breath and don't let it ruin your trip

We always checked our car seats with the luggage and checked the stroller at the gate. Liquids 4 ounces or less are generally fine. Anything bigger will get taken from you. Also they have water and (usually) a few juice choices on the plane. I don't think they make kids go through the body scanner, just the regular one.
Check with your carrier (airline) for specifics.
We have traveled for many years with three kids, from birth to teens and other than the usual headaches (flight delays, cranky kids, annoying passengers) we have never had any real problems.
Traveling is an adventure, have fun!!!
ETA: if you are only traveling with one child you probably don't even need the stroller, it's often more of a pain than it's worth.

I didn't use a cart for the car seat, so I don't know that one. We used a luggage strap to hook the car seat to our rolling carry on bag, and used a real stroller for the airport. That is if you plan to use the car seat on the plan. If you don't plan to use the seat on the plane, then did you know that you can always check car seats for free?

No, I wouldn't try to take juice through. All airports have places that sell drinks, including juice, after you go through security. I take an empty sippy cup, so that after I go through security, I can buy juice and fill the sippy.

My kids go through the body scanner. Someone else said below they don't, but that is not my experience. My kids have always been required to go through. I suppose you could ask for them to be patted down instead, but that seems more intrusive to me.

I've never encountered a TSA agent that was bad with kids. Some are friendly, some are businesslike, but I've never had anyone be rude.

I'd check my car seat at the ticket counter (unless you plan on using it on the plane) and forget about having it in the airport. You will have to take your child out of it to go through security, put the cart and the car seat through the scanner and it's a lot to deal with when you have all your other stuff plus a 2 year old. In my experience it was easier just having my kid walk or carried through the airport than trying to deal with a stroller they don't want to be in anyway. The last time I took a stroller through the airport it went something like this:
In the stroller to the ticket counter
Out of stroller at security
Fighting to get back in the stroller after going through security
Getting out of stroller when we got to gate to have them run around so they would sit better on the flight.
Dealing with gate checking stroller
Waiting for stroller after getting off of plane
Kid not wanting to go in stroller because they just sat for a few hours

That was it. I don't bring strollers or car seats through the airport. I check everything at the ticket counter. Way less stressful for me than dealing with everything associated with bringing a car seat or stroller through the airport.

If you are bringing the car seat for travel in the plane, I know they sell carts at Buy Buy Baby. I wouldn't invest too much money in one if it's just for one trip. I would actually checkout craigslist or a second hand store for one.

As for liquids, the only things that can go through security are medicines, formula, BM, and liquids under 3 oz in proper containers and a sippy cup is not a proper container, so it would be dumped. I know it's more expensive, but it's also easier to just buy it after you get through the airport.

For me, my time and less stress is worth the extra money to buy things after you get through security and just deal with a 2 year old walking through the airport. I have two 2 year olds and I still plan on not having car seats or strollers with me through the airport.

You do not want your kid going through the scanner because it may harm him. I don't want want your kid to NOT get scanned because that oversight may harm a whole plane of people!

You will be fine. Check the TSA site before you leave to see what you can and cannot carry through security.

You can buy special drinks and juice after you go through security... no big deal, plenty of places to get something for your little one.

We fly a lot and I have not seen little kids going through the scanner but either way, it is no biggie takes 5 seconds or less.

Just relax and enjoy your trip.

Eta: don't count on boarding early. Most airlines no longer preboard for families anymore. Most preboards are wheelchairs and children flying alone.

I have flown a lot with my kids since they were babies (now 3 and 6). TSA agents are generally quite good with little kids. Some will give them TSA badge stickers, ask them about where they are going, etc., some will just be polite, but we have never had a "mean" one, and that covers at least 10 states and a dozen or more different trips. As far as juice, it will depend on the specific agent. I have had them allow a sippy cup and applesauce through, but I was prepared to dump it if needed. Maybe bring a juice box or something that you can toss quickly if refused. Children under 12 can keep their shoes on. You can always refuse to go through the scanner, but may be subject to a pat-down. Your toddler can't go in the scanner for the simple reason that she likely can't stand in place long enough! In general, don't worry, it will be fine!!

Take the small juice boxes - they are expensive but they are acceptable. Then you can toss them as they are used. Take snacks in baggies so they can be compressed or tossed as things are eaten.

Take a bunch of new, small travel games/toys - things that are quiet to play with but will be BRAND NEW to her. Play Dough is okay (take a sheet of wax paper for the tray table if you want to), Duplos can work if you have the space. Get some books from the library so you don't have to pay for those, or go to a children's resale shop, or get something on your Kindle if you have one. Set aside some for the terminal itself, others for the plane. Only show her one at a time - don't let her see that there is a treasure chest!

I've seen some people make up goody bags for those in adjacent seats - the 3 in front, the 3 in back, and the 3 across the aisle. They put in all kinds of stuff, like disposable ear plugs, a package of crackers, and some hard candies and so on, with a note that says "we are traveling with a toddler and hope things go well but we also hope you have a good flight". Usually they use a clear plastic bag tied with a piece of curly ribbon with the note attached. Since parents pre-board, you can leave these bags on the seats before the other passengers board. Seems like a lot of effort but it can smooth the way with cranky adults!

Since you will board early, you will be guaranteed overhead storage by your seats, so everything will be close by. I have mixed feelings about bulkhead seating vs. regular. Bulkhead gives you more leg room but no space under the seats ahead of you for your things. And I think the tray table is good for toddlers and children.

The agents are usually good with kids - they are used to it especially as summer approaches (and they've just been through spring vacations).

The car seat is ideal on the plane because the child is already used to it in the car, and then you have it on the other end. You can gate-check a stroller (regular or umbrella) and you can just put your carseat and bags on the rental luggage cart if you need to, unless you can strap the carseat to a larger bag (probably cumbersome but it will get you to baggage check if they don't have it curbside).

Gogokidz.

Kids don't go through scanners.

We checked out carseat and took an umbrella stroller for walking from gate to gate. Kids can take sippy cups (my son's just had water, I offered to dump it out and the TSA agent said it was no problem and he could keep it), they just open it up and check what's in it using a strip. They sent me and the kiddo through the regular metal detector rather than the body scanner. I stressed alot about it, and it was really an easy experience.

We always check the car seat with our suitcases. It is a lot less hassle. The various car seats we have had were not approved for airline use and were too big to fit in the seats anyways. There is no charge for car seats. Just take your stroller into the airport. An umbrella stroller would be the easiest to use. You check that at the plane. Just ask for a stroller tag at the gate desk.

I think you will probably just want to wait to buy juice once you go through security. Liquids that you take through security have to be in 4 oz sized containers. Beverages have to be in their original containers. (Unless it is breast milk or formula.). If you can find juice boxes that are 4 oz you would be able to take a limited number of those through. I think they say "a reasonable amount for the length of your trip." You might find a TSA agent who would let larger juice boxes through, but they are rare. If you can wait until you get on the plane and they do the beverage service you can get a glass of apple juice.

Children do not go through the body scanners. They still have the "old fashioned" metal detectors for them to go through. They will also let you go through that. They will usually have the child walk through first and then let you follow behind. I have never gone through the body scanner because I'm always with my kids. Kids can keep their shoes on now.

TSA agents are usually pretty patient with kids if the parents are being responsible and prepared. We just flew and the TSA agent gave the kids stickers after they got through the line. Any liquids and gels (even lipstick/chapsticks) need to be in a clear ziplock Baggie. Have it in an easy to reach pocket of your bag so you don't have to dig for it. Wear shoes that are easy for you to take on and off. Remember to take off jackets and take everything out of your pockets. Avoid wearing belts or jewelry that could set off the metal detector. Have your stroller ready to fold up and put on the conveyor belt. Any loveys or blankets your child might be carrying have to go into the tray. Be anticipating everything that needs to go through the x-Ray machine and be prepared so you don't have to fumble around to get it all up on the belt. If you aren't holding up the line, TSA will be much more patient.