Ly-alpha tomography surveys have produced 3D maps of the Lya opacity of the intergalactic medium (IGM) at z ~ 2.5 with Mpc resolution, offering a new window to discover high-redshift large-scale structures like the progenitors of present-day massive galaxy groups and clusters. This presentation explores the complementarity of Ly-alpha tomography with conventional galaxy surveys. In the largest IGM map to date, the Lyman-α Tomographic IMACS Survey (LATIS), we detect both previously known galaxy protoclusters and a novel population that was missed by galaxy spectroscopic surveys. I also present our independent constraints on the stellar vs. halo mass relation from LATIS tomography. Additionally, I'll discuss our recent work demonstrating synergies between these tomographic maps and the upcoming line intensity map (LIM) experiments at cosmic noon. This cross-correlation allows one to detect emission from the faintest galaxies, enabling unbiased cosmological and galaxy evolution studies. Throughout the presentation, I will share our progress to date and the promising prospects for the future, covering both the modeling of these new mapping techniques using the largest cosmological hydrodynamic simulations, which is required to fully realize the potential of these techniques, alongside the latest observations in this emerging field.