China's Spring Festival travel rush, also known as Chunyun, is the largest annual human migration on earth. The travel rush lasts for 40 days and Chinese officials expect a record nine billion passenger trips this year. With China extending visa-free travel to a growing list of countries, a Chinese New Year travel boom is on the horizon. What is new about this year's Chunyun? How do people choose their holiday destinations? What can we learn from thriving holiday spending?