I would like to go to Qinghai in February, with my 2 daughters. What should we visit for 3-4 days?

Hey, it's too cold to visit Qinghai in Feb. If you really want to go there, you may visit Qinghai Lake, Chaka Salt Lake and Ta'er Monastery. The lakes become icy in winter. In fact, the best time to visit Qinghai lake is in July and early August. At that time, the weather is cool and you will see a sea of cole flowers.