Transition strengths measured with two complementary experimental probes can be used to disentangle neutron and proton contributions to collective excitations. Several experimental probes with various sensitivities to neutrons and protons, including electron, nucleon, and pion scattering, Coulomb excitation, and gamma-ray lifetime measurements, have been used in this way to study stable nuclei. Since the 1990s, this approach has been extended to exotic nuclei via comparisons of proton scattering in inverse kinematics with electromagnetic probes, like Coulomb excitation. These efforts have provided insights into the evolution of shell structure and shell-model effective charges away from stability. I will describe the experimental techniques used at the NSCL, and outline plans for advancing this program at FRIB.