Of course it is Yunnan! September is not the rainy season, and the weather in Yunnan will not be too hot. Fifteen days is enough to go to Lijiang, Dali, Lugu Lake, Shangri-La, and Xishuangbanna. Hope to help you! Hope to "adopt"
The 4 places you choose are most suitable for long-distance travel. The Taiwan train tour around the island is more innovative and interesting than the other three attractions.