RadioGirl, There is another aspect of all this that you might not have considered.
You need to save wear and tear on yourself!
As an older woman, I can tell you that I've already made the mistake of not doing so!
Consider your body as an investment account. Treat your body kindly and it will return the favor later on in your life.
American airports are often HUGE. Treating yourself kindly will help to prevent wear and tear on your body.
With medical advances coming along, you need to be in the best possible shape to benefit from them.
I wish someone had told me this 25 years ago!
Bon Voyage!