Chengde and Qinhuangdao are better. There must be different opinions, and no unique conclusion can be drawn. But from the perspective of summer vacation, I can tell you that Chengde is superior to Qinhuangdao. The main factor of summer vacation is climate. The summer climate in Qinhuangdao is low temperature and high humidity (that is, the temperature is cool and the humidity is high), and that in Chengde is low temperature and low humidity (that is, the temperature is cool and the humidity is small, and there is dryness in the cold). So Chengde is more suitable for summer vacation.