I recently took my 2.5 month old son to an all inclusive resort in Mexico. Yes, I am crazy, but it was kind of important to go, because I was getting married there.
Before the trip I searched online for tips about traveling with an infant and found some helpful articles, but nothing that gave advice that wasn't common sense. So I thought I'd contribute some not as obvious thoughts for those who could be in the same situation as I was.
Pack an extra outfit for the baby and yourself on the plane
As you probably already know, babies poop a lot. I had the fabulous fortune of having my son do a blow out right as we were landing in Cancun, with a 20min delay on the tarmac. Poop leaked all through his clothes onto my arm and leg. Luckily I had an outfit to change him into, but I didn't have one for myself, so I lived in poopy clothes that day.
Even if you don't have a shit storm happen on the flight, a cooler weather appropriate outfit is a great idea to change your child into before you land; The Cancun airport was super hot and hardly Canadian winter clothing appropriate.