@Floradon We used a holiday company to put together our itinerary. This is roughly what we did.
We started off in Shanghai and finished in Chengdu. In between - train to Beijing and flight to Xian.
Shanghai has a superb museum with clothes from different areas, ceramics, coins, and bronzes amongst other art works. The River and Financial area is futuristic and the old areas have character. We also went to the canal town of Tongli but you could go to Suzhou. More developed but bigger. Have a look at the Prosperous Suzhou scroll. It’s fantastic.
Beijing - obvious places to see here but you must see the Great Wall. The nearest access point to Beijing can get crowded so go to Jinshanling or Mutianyu access points. Less people but November might be cold! Check the weather. These areas are exposed. It’s a do not miss though!
We went to Guilin and also went to the rice terraces. The scenery around Guilin is beautiful but very much a tourist area. We also stayed at Longii in the rice terrace area and was great.
Xian has many treasures and go to the Shannon museum as well as the warriors. The warriors are spectacular but there’s also the tombs of Emperor Jingdi. Han dynasty tomb and less visited. It’s near the airport. The walls are immense and the pagoda is fantastic. There’s puppet shows to see and there was a bouyant Muslim quarter. Hope it still is.
Chengdu - we just had to see pandas! Fascinating seeing the cubs. Memorable visit. You can travel out of the city to see a giant Buddha and there’s various temples to visit too.
Steppes Travel and Audley Travel have great itinerary ideas. Not sure I’d do DIY in China. I like Abta protection! We organised flights and did bespoke tour for us once in China. You will need to look carefully at excursions if you DIY and I’d use a planning book such as Lonely Planet. Chinese guides tend to rush you around and miss important sights out. You need to know what you will actually visit and if you have time for what you want to see.
The UK Government has full details about going to Tibet. It’s not a DIY destination.