Due to job constraints, you're allowed one 3-week vacation every year to travel the world. You're young and have never been outside the United States before. Money, within reason, is no object. Over the next couple decades, you want to see as much as the world as possible. What's your strategy?
When I started traveling, I thought I would love Asia most of all and be least interested by Latin America. The opposite has turned out to be the case. Since most people are not good at forecasting which places they will like, I suggest a simple strategy: see each major world area as rapidly as possible and figure out where you love it most. Then concentrate your attention there.
Here are a few three-week trips you might take:
1. Europe: Amsterdam-Paris-Switzerland-Florence-Rome
2. Latin America: Mexico City-Macchu Picchu-Buenos Aires-Rio (don't shoot!)
3. Asia: Tokyo-Hong Kong-Shanghai-Bangkok
Also, figure out whether you want vacation or travel; I love the latter and hate the former. I much prefer work to vacation, and use work to recover from my travel. That entire distinction is usually more important than where you end up going.