I just came back from an international trip that included plane changes, taxi rides and boat rides. I carried all of the things below:

-large laptop bag
-floss, toothbrush, toothpaste
-camper's toilet paper (Walmart)
-extra undershirt, underpants & socks
-bandana
-laptop
-cell phone
-chargers
-adapters
-AA & AAA batteries
-regular survival kit: flashlight, Bic, whistle, mirror, paracord, basic First Aid, etc.
-leisure reading
-beanie
-sun hat with wide brim
-hooded ski jacket (on me usually)

If I'm traveling through frigid airports, I'll carry clothes for cold weather. I've had my luggage get lost before on a stop through Denver I think it was. I had to spend the night in the airport because I missed a connection. The heat shut off for several hours in the early morning hours. When I travel with my fiance, I have to double up some things. I expect her to carry none of that stuff, but of course she still expects me to have what she needs.

I may sound lame for saying this: I don't enjoy air travel anymore. It's too complicated. If I can get similar enjoyment by driving somewhere local, then I'd rather do that.