There are lots of exciting sites in China, but it depends on what you aer looking forward. If you primary interest is major cities and cultural history, I would strongly recommend a visit in the old Nationalist capital of Nanjing at the Yangtze - only 3 hours by train from Shanghai. In the Shanghai area there are the beautiful cities of Suzhou and Hangzhou as well. Both with ancient Chinese buildings, lakes, canals and pagodas. Definitely worth a visit.
For experiencing nature and the less modern Chinese, go west. Chengdu is a calm (by Chinese standard) city, and a good base for exploring sites as panda preserves, and especially the amazing mountains of Emei (Emeishan), where you can hike to the top through a beautiful scenery, and eventually taking the night break at a lonely monastery.
You might also take a look at the Yunnan province. the regional capital of Kunming has lots of beautiful scenery nearby, and it is a great base for visiting the astonishing mountain cities of Dali and Lijiang, which host yet more beautiful nature, and are the homes of some of China's minorities.
As another one suggested, the Guilin area has spectacular landscapes. If you choose to visit, head for Yangshuo just south of Guilin. The boat ride between offers amazing scenery comparable with the three gorges, but it is heavily touristed. Stay in Yangshuo to rest for a few days. Rent a bike an take a trip in the countryside among the big Karst hills and the rice paddies.
All the above mentioned places are easy to get to. They are all reachable by train and most by air.
I you have any questions, feel free to ask
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