// Vector3.Lerp – linear interpolation
euler3 = Vector3.Lerp(euler1, euler2, alpha);
cube1.transform.rotation = Quaternion.Euler(euler3);
// Quaternion.Slerp – quaternion spherical linear interpolation
quat3 = Quaternion.Slerp(quat1, quat2, alpha);
cube2.transform.rotation = quat3;