The world looks very different if you are standing on your head. I would not recommend that you make this your default, but arguably standing on your head for up to 30 minutes in a day makes your world a better place. Yoga has been advocating a headstand or Shirshasana for millennia. The reasons are manifold and so if you are tired of being on your feet try your head instead.
When standing, gravity works against you and your heart has to work hard to circulate blood through out your body especially your upper body. If your heart is not strong, this can result in weak blood flow. The first major benefit of a headstand is the positive impact that it has on your lymphatic system. Your lymphatic system is a complex system that detoxifies your body using white blood cells. A headstand helps flush out many toxins reducing the strain on you. While doing a headstand, blood rushes to your head and scalp which improves the circulation bringing vital nutrients to aforementioned parts. Your cheeks get flushed and you feel the rush of blood to your head. It almost feels like you are falling in love. Again? Many of us suffer from edema or the build up of fluid in the legs. Headstands reduce this build up of fluid. A headstand reverses the pull of gravity on your intestines. This acts as a flush for your intestines and removes congested blood in your colon. The outcome is a more efficient digestive system. Finally, a headstand gives your heart a break by reducing the effort it has to make to pump blood for the duration that you are on your head. This reduces the risk of cardiac ailments.
I would not break into a head stand at an airport unless you suddenly have an uncontrollable desire to be on television. Otherwise, unless you have high blood pressure, neck or spine injuries or some other contra indication based on which your doctor has advised you not to, a head stand can be a wonderful way to spend 30 minutes musing on the world passing by.