A gas turbine that includes a rotor blade that includes an airfoil. The airfoil is defined between a pressure face and a laterally opposed suction face, the pressure face and the suction face extending axially between opposite leading and trailing edges and radially between an outboard tip and a connection with a root of the rotor blade. The airfoil may include non-integral portions in which: a base portion of the airfoil is made from a first material; and a top portion of the airfoil is made from a second material. The airfoil may include a dovetail joint connecting the top portion to the base portion. The dovetail joint may include a dovetail extending from the top portion being received within a complementary dovetail groove formed in the base portion.