In four days, it will be too late to go to Lugu Lake. Lijiang and Dali are recommended. The proposed itinerary is as follows:
Day 1: Arrive in Lijiang, visit Old Town of Lijiang, and go to a bar in the evening. There may be an affair.
The next day: shuttle bus to go to dali, visit the three pagodas of Chongsheng Temple, the landmark landscape of Dali, and go to Shuanglang in the afternoon.
Day 3: Watch Erhai Lake while having breakfast in the morning, and experience the petty bourgeoisie. Maybe go to Nanzhao Style Island or rent a bicycle to ride. You can stay for a few days if you have more time, and return to Lijiang in the evening.
Day 4: You Shuhe Ancient Town, Lashihai. Fly home at night. If four days is a pure play for four days, you can also go to Tiger Leaping Gorge or Yulong Snow Mountain.
Inn recommendation: Lijiang Ancient Town: Zhenmei Chain Lion Mountain Store, with free fruits and snacks, and a free observation deck overlooking the city. It is located in Wangulou and a little higher. It is a small courtyard with three floors, very quiet, and the standard room is above 200 yuan, with quite high cost performance. Recommend it to you, you can look at other people&;s comments online, and all major travel websites can make reservations.
I wish you a pleasant journey, and I hope it can be adopted as the best answer. Thank you!