The evidence for the existence of dark energy is conclusive, but its nature remains one of the most puzzling mysteries in all of physics. Astronomical surveys that map the large-scale structure of the universe offer the best opportunity to solve this mystery experimentally. These same surveys also provide an unparalleled resource for studying the structure and evolution of the most massive galaxies over cosmic time. I will present both cosmological and galaxy-evolution results from the Baryon Oscillation Spectroscopic Survey of the Sloan Digital Sky Survey III, with a focus on work done by my research group at the University of Utah. We are finding new evolutionary trends by employing new methods to extract the signals of massive-galaxy demographics from deep in the large-N, low-S/N regime. These same methods will ultimately be the key to delivering precision constraints on the physics of dark energy from the next generation of cosmological redshift surveys.