A turbine blade that includes an airfoil and a radially extending chamber therein for a coolant. The turbine blade may also include a rib configuration that partitions the chamber into radially extending flow passages. The rib configuration may include: a camber line rib that defines a near-wall flow chamber; and traverse ribs extending between the camber line rib and one of the outer walls so to divide the near-wall flow chamber into successively stacked flow passages that each include a segment of the camber line rib. The segment of the camber line rib of one of the flow passages may have a narrowing profile that includes a profile that narrows from opposing ends toward a neck disposed therebetween.