All babies are different, of course, but after 3 kids, I absolutely agree that the easiest age to fly with (until they're about grade-school age) is infant until about 9 months. They're not mobile yet, and they can usually be soothed with breast, bottle or pacifier. My kids are now old enough (almost 5, 7, and 9) to be reliably entertained by books, tablets, etc. through almost all flights, but when they were toddlers, I found myself wishing that we had done a lot more traveling with the oldest when she was a baby and still the only one!
You've gotten good advice so far--my top flying with baby recs are:
- Be prepared with plenty of extra formula/bottles just in case (TSA has really eased up on this from what I've seen), or be ready to nurse a lot
- Have pacifiers handy if your baby takes them
- If you don't have one of these, Google "baby safe feeder"--if you've started your baby on solids at all, these things are *awesome*. They're like a giant pacifier with a little screw-off net bag at the end, into which you can put pretty much any food you're eating. Baby can gnaw at it to his/her heart's content and get whatever tastes of the food come through the tiny holes. Apples and pears are great in these, but we've put tons of different foods in them.
- Put more diapers than you think you'll need in your carry-on, a full container of wipes, two changes of clothes for baby and at least one for you. The time you don't pack your change of clothes will be the time the baby decides to have explosive diarrhea all over you, five minutes into the flight.\\
Have fun!