We address the optical physics of surface-enhanced stimulated Raman spectroscopy (SESRS) from the microscopic to macroscopic scales to provide experimental design criteria in colloidal-suspension SESRS. The nanoparticles that provide local field enhancement also extinguish the Raman signal. We compute the total Raman signal detected from a suspension of Raman-active molecules and nanoparticles due to the cumulative effects of enhancement and extinction and find optimum operating parameters for pump frequency and nanoparticle concentration.