What I would do is unlikely to be what you would... There is a huge difference between 2 and 4 weeks. With 2 weeks I'd possibly go to Antarctica because that's

What I would do is unlikely to be what you would... There is a huge difference between 2 and 4 weeks. With 2 weeks I'd possibly go to Antarctica because that's the only continent I haven't yet visited. With 4 weeks I'd visit the Galapagos, and walk some of the Inca Trail to Machu Picchu. Or I might go to Greece. Btw a decade ago I traveled around the world for one year, for less than that amount. Best year of my life.