Visiting the Summer Palace during peak and off-peak seasons each has its own merits. During the off-peak season, there are fewer people, but the mountain areas may be closed due to dry weather (snow scenery is highly recommended). During peak season, it's more crowded but fully open (June is recommended; it's said that the number of visitors can reach 130,000 during the summer holidays in July and August).
It's advisable to book a guided tour in advance through various platforms (entrance fee not included). They know the routes and all the secrets inside and out like the back of their hand (39 yuan per person for a large group of 30 people, generally 270 yuan per person for a small group of 10).
I've tried my best to recall some of the highlights our guide mentioned:
1️⃣ Generally, four-character plaques are in the handwriting of Emperor Kangxi, such as "Bishu Shanzhuang" (避暑山庄). Three-character plaques are mostly in the handwriting of Emperor Qianlong, because this intelligent emperor said that the number of characters in his inscriptions would not exceed that of his grandfather.
2️⃣ The character "避" (bi) in "Bishu Shanzhuang" has an extra horizontal stroke. There are many theories about this. Some say it's for the sake of a fuller and more aesthetically pleasing calligraphy style, while others say it's to distinguish it from the meaning of "refuge," creating an alternate form. The meaning of protection is now clear.
3️⃣ The priceless residence in the Summer Palace Museum: 48 golden nanmu pillars, mainly located in the Danbo Jingcheng Hall. If we consider golden nanmu as priceless treasures, then the Summer Palace itself is also priceless.
4️⃣ The museum contains 6 replicas, reportedly damaged during transport by staff in the early days of its construction. If not for this human error, they would all be genuine. (This reminds me of an old podcast where a museum staff member put an artifact in a cardboard box, picked it up, and the bottom punctured, shattering it. The staff member was even docked eight yuan from their bonus for damaging the artifact and remained depressed for the following year. A truly regrettable situation.)
5️⃣ The Qingyang Study next to the Misty Rain Pavilion is said to be the place where Emperor Kangxi and Emperor Qianlong interacted and exchanged ideas.
6️⃣ The plaque of the Misty Rain Pavilion was inscribed by Emperor Qianlong. This plaque is a replica. The original artifacts are on display at the Chengde Museum.
7️⃣ Yanyu Tower and Shufangzhai were filming locations for "Princess Pearl" (Aunt Qiong Yao seems to particularly like the Summer Palace; "Looking for Husband Cliff" and "Xue Ke" were also filmed here. However, it's said that regulations were later introduced prohibiting filming within the scenic area, so it seems you should do things early).
Last for the best! Remember to wish yourself good luck: 1️⃣ Wash your hands with the water of the Rehe River for a year of good fortune. 2️⃣ Walk clockwise three times around the Shangdi Pavilion on Jinshan Island for blessings, wealth, and health.