Huanglong is a real fairy tale landscape with autumn leaves, frozen waterfalls and ponds colored blue through yellow make Huanglong a surreal place. I visited in 2018 after a business trip in Beijing. I always flew in to Chengdu (great KLM fares). Huanglong is just 150 kilometers from Chengdu but through the mountains by road I would not recommend. Take a short flight to Jiuzhaigou airport and stay in a hotel there. From Jiuzhaigou it's a 1.5h drive to Huanglong. A day trip suffices. The entrance fee is huge. Avoid visiting during Chinese holidays as you will regret that. Keep in mind that during November at some point the cable car stops for the winter and opens again in spring.
Huanglong is located at an altitude between 1700 meters in the lowest valley up to 5588 meters at the highest peak. Huanglong is made up of various cascades of natural pools behind travertine dams. Travertine is a kind of limestone and forms at hot springs when calcite from the water precipitates. That means that solved calcite dissolves rapidly due to a change in pressure. This calcite forms the limestone dams but can also form stalactites, stalagmites and tufa
I arrived to the upper part of the Huanglong valley by cable car. There are a total of 14 main scenic spots within the valley. Multicolored lake, the upper and lower temple, flamboyant pont and other points with lovely names. Not to forget the golden sand, washing cave waterfall (frozen in November) and also hotsprings.
This natural site for me deserves for sure a 4.5 star rating if not 5. The half point due to the high entrance fee.