This Southeast Asian hub, which served more than 50 million passengers in 2012, has taken the top spot on the Skytrax rankings multiple times over the past decade. Passengers on a layover here have options. Changi boasts a “nature trail” with six separate gardens representing different eco-systems. Lounges with plenty of “napping areas” are also available, along with fitness centers, massage chairs and a swimming pool. People who have a layover of five hours or longer can take a special guided tour of Singapore. If you’re a shopping enthusiast, you might just want to stay in the terminal. More people shop in Changi each year than in any single mall on the city’s famed Orchard Road.