Ni-based superalloys are used extensively in high temperature applications. With excellent creep and fatigue properties along with good corrosion resistance, Ni-based superalloys are an optimal design material for turbine blades and other high temperature, high strength applications. While superalloys have been used for decades, recent works have begun to reveal that, during deformation, solute segregation to planar defects are influenced by alloy compositions. In this work, our recent alloy design strategy via the CALPHAD method and experimental findings including creep results of γ’-containing Ni-30Co-Al-X-0.03Zr-0.5B (X=Ti,Ta,Nb) are presented. Based on these findings, we hypothesize that the presence of Co provides a driving force for segregation to planar defects. Furthermore, it has also been proposed that alloys whose compositions lie close to the γ+γ’/γ+γ’+η/δ phase boundary (low Al, high X alloys) would exhibit a propensity for segregation of η- and δ-formers to SISFs and SESFs.