A turbine blade having an airfoil defined by a concave shaped pressure side outer wall and a convex shaped suction side outer wall that connect along leading and trailing edges and, therebetween, form a radially extending chamber for receiving the flow of a coolant. The turbine blade may further include a rib configuration that partitions the chamber into radially extending flow passages. The rib configuration may include a camber line rib having a wavy profile. The wavy profile may include at least one back-and-forth “S” shape.