The last week in May, we will be in China for 1 week, half in Hong Kong and then Beijing. Any tips

At the point of weather, it will get very hot then, so you are advised to take some summer clothes. Also some rainy days may happen then. U can prepare simple rainy gear also!

Thank you. Does it get cold at night? Are there any especially good shopping areas to hit at either city.

Please do not worry. It will not become cold at night. From May, summer will come to both of the cities, so no big temperature difference will exist.

For shopping in Beijing, the Wangfujing and Xidan area are suggested. For HK, it is suggested to go to the Tsim Sha Tsui and the Causeway Bay area.