At both Auckland and Heathrow airports I saw similar scenes - tears and hugs. The goodbyes in the departure area were mostly sad, as opposed to the happy, sometimes ecstatic, scenes in the arrivals area.
Those emotions are part of what makes us who we are, and if I take this back to writing, how our characters show their emotions can make them a memorable three-dimensional character, or a cardboard cut-out.
I read a blog entry just before leaving Auckland which mentioned that a character shouldn't cry more than once in a novel because it became boring and trite, and as people we show emotions in multiple ways.
Getting to know our characters means we know their particular traits and mannerisms as well as we do those of our close friends and family.