Traveling from China to Thailand

During your stay in Beijing, you can see the pandas in local zoo. If your time permits, I suggest you have a short trip in Tianjin too, which is only arouind half an hour distance by bullet train from Beijing.

Apart from the major attractions in Shanghai, you are also recommended to go to Suzhou or Hangzhou for a visit. In Suzhou, the Silk Museum and classical gardens should not be missed. In Hangzhou, I highly recocommend the West Lake and the local cuisine in Lou Wai Lou.

To see more pandas and possibly hold a panda baby, you are recommended to fly from Shanghai to Chengdu then. At the Chengdu Panda Breeding and Research Center, you have a special experience with pandas.

There is direct plane service from Chengdu to Wenzhou then. And the direct plane between Kunming to Bangkok is available.

As you have limited time and would like to visit so many places during that period, I don't suggest u travel too many cities, because you will be very tired. Generally, here is my suggestion:
4-5 days in Beijing: the Forbidden City & Tiananmen Square, Summer Palace, Badaling or Mutianyu Great Wall and Ming Tombs should not be missed. As you wanna see the pandas, go to the local zoo for fun.

Then take a high speed train to Shanghai for a visit. There you can enjoy yourself on the Bund, in Oriental Pearl TV Tower, Jin Mao Tower. If you have time left, go to Zhujiajiao Water Town for fun. For shopping, local Nanjing Road pedestrian should not be missed. You can stay there for 2-3 days.

After that, take a high speed train to Suzhou to see the Classical Gardens. In the next day, again use a fast train to Wenzhou. Maybe you would spend several days there. After that, fly to Kunming to prepare for your leaving for Bangkok.