For group building, Huairou, Miyun and Du Shi are all ok, mainly depending on what you want to do.
Generally speaking, we often go to Gubei Water Town, Wuling Mountain, Water Great Wall, Qinglong Gorge, Dushi and Yesanpo.
People in Gubei Water Town can consider living in the light of Gubei, and it's good to see the night view at night.