Do I need a visa? Thanks a lot!!

Hi, my family and I are flying from Dallas to Beijing (staying 3 days) and then flying from Beijing to Vietnam. After Vietnam, we return to China, but via Shangai for 2 days before heading back to the US. Do we need a visa or it qualifies under the 144hr transit? Got confused because we are going to 2 different cities in China but not in the same entry.