India, July 16 -- After 10 years of flying around the world as a full-time travel writer-I once touched down on all seven continents in one calendar year-I've got packing down to a science. While most travelers focus on what they have on wheels, I've learned the hard way that it's what's in the pack strapped on your back, hung over your shoulder, or worn arfeaound your waist that matters most. After all, these days it's not uncommon for luggage to be checked at the gate. (That's why you should never put your passport in your carry-on.)

My personal item, the Cotopaxi Allpa 35L Travel Pack, has served me well on flights to approximately 70 countries. And while I tailor what I bring to each destination, there are some items I always pack in...