The CARES harness!
On international flights you can get a bassinet, which hooks into the wall of the bulkhead. Make sure you request it in advance so they seat you in the right row, and request it again as soon as you get on the plane. There are a limited number available depending on the type of aircraft, and don't expect the airlines to actually keep track of how many people requested them versus how many are available! We used one to go to Guam, and we ended up sharing with the people next to us, since they ran out of bassinets. It wasn't that bad, but it's always preferable to get your own!
Activities! We are building up a collection of travel toys. They can only be play with during travel, which makes them more exciting. Some of our favorites are:
The Go Art watercolor kit
The find-it square
An ink pad. This was a surprise for me. At the airport, I bought the tot an ink pad set for $5, with a tiny book and a pen. You stamp your fingers and use the pen to draw ears, feet, etc. to make little animals. The book gives a lot of ideas. (We have a book like this at home, but it's bigger and was, well, at home.) It kept her occupied for a LONG time! I was so surprised. She did the stamping and I did the drawing. I used wet wipes to clean her up and didn't even have to get out of our seats.
The great stroller conundrum. Do you risk the life of your "good" stroller for the convenience of having it at your destination, or do you use the cheapest back-breaking umbrella stroller you can find? Up until this point we went with the umbrella stroller, but I decided she would need the sunshade in Louisiana and I wanted to stash the carry-on bag underneath it so we risked the good stroller. And they destroyed it.
Lazy airline employee #3467 dragged the stroller by one of the straps, which ripped not only the fabric but the padding in the seat and the stitches that hold the strap in. I am awaiting compensation, but am not optimistic. Well, lesson learned.
Best of luck on your next travels!