Suggest you get to the city center of Tianjin to see the Old Cultural Street, Confucius Temple if you like and Haihe River (there are parks and other scenes along the river). Shi Ba Jie Ma Hua (fried dough twist and Shi BA JIe brand is the most famous), Gou BU Li Steamed Bun and Er Duo Yan Zha Gao (deep-fried cake) are the must try snacks of Tianjin, you can buy some home. :-)