21 days in China - Sep 2026 - First timer looking for feedback on my itinerary

I've been planning this trip for months and would love some feedback from people who've been. This is my first time in China.

Beijing (Sep 3-6, 4 days)

• Day 1: Arrive 4:40 AM, rest, Wudaoying Hutong, Lama Temple, Confucian Temple
• Day 2: Forbidden City (full day), Jingshan Park sunset, Nanluoguxiang evening
• Day 3: Great Wall — Mutianyu (cable car up, toboggan down), Peking duck dinner
• Day 4: Temple of Heaven (early for tai chi), China National Museum, Summer Palace, Houhai Lake evening

Xi'an (Sep 7-9, 3 days)

• Day 1: Train from Beijing (~4.5h), Bell/Drum Tower, Muslim Quarter street food
• Day 2: Terracotta Warriors (full day), Big Wild Goose Pagoda
• Day 3: City wall cycling (14km loop), Shaanxi History Museum

Chengdu (Sep 10-13, 4 days)

• Day 1: Train from Xi'an (~3.5h), Wuhou Shrine, Jinli Street evening
• Day 2: Panda Base (early AM), People's Park teahouse, Sichuan Opera evening
• Day 3: Leshan Giant Buddha day trip (DIY by train, river cruise + cliff walk)
• Day 4: Kuanzhai Xiangzi alleys, cooking class or hot pot crawl, night market

Zhangjiajie (Sep 14-16, 3 days)

• Day 1: Train from Chengdu (~5h), arrive evening, rest near Wulingyuan
• Day 2: Yuanjiajie (Avatar mountains), Golden Whip Stream
• Day 3: Tianzi Mountain + Tianmen Mountain (glass skywalk, 999 steps)

Hangzhou (Sep 17-18, 2 days)

• Day 1: Train from Zhangjiajie (~5-6h), West Lake sunset walk
• Day 2: Lingyin Temple, Longjing tea village, West Lake boat ride, Hefang Street

Shanghai (Sep 19-23, 3 days + departure)

• Day 1: Train from Hangzhou (~1h), French Concession, Nanjing Road, Huangpu ferry
• Day 2: The Bund, Yu Garden, Propaganda Poster Art Centre, Pudong skyline evening
• Day 3: Jing'an Temple, Tianzifang, AP Plaza, ERA acrobatics show
• Day 4: Suzhou day trip OR spa day
• Day 5: Free morning, PVG for 8:10 PM flight

Questions for you:

1. Is Tianzi Mountain + Tianmen Mountain doable in one day, or should I split them?
2. The Zhangjiajie → Hangzhou train — is the Changsha transfer smooth or should I plan extra time?
3. Anything on this itinerary that's a tourist trap I should skip?

Thanks in advance!