The circum-galactic medium (CGM) is at the nexus of the gas inflows and outflows that regulate galaxy evolution. Consequently, the CGM provides an ideal laboratory for studying galaxy fueling, feedback, and interactions. Historically, studies of the CGM primarily relied on background absorption spectroscopy which enables uniquely sensitive probes of intervening gas but typically lacks the spatial information needed to differentiate the origins of CGM gas flows unambiguously. Recently, the advent of wide-field optical integral field spectrographs enabled the discovery of giant (>50 kpc) scale CGM nebulae around quasars in non-resonant, rest-optical emission lines, providing unique 3D (2 spatial + velocity) maps of the CGM. I will present results from ongoing emission surveys of giant nebulae around ~30 z < 2 quasars that directly trace accretion, debris from interactions, and AGN outflows. Finally, I will discuss possibilities for future discoveries based on emission studies of the CGM enabled by a next-generation UVOIR telescope capable of spatially resolved spectroscopy.