We present an overview of our analysis of over 200 protoplanetary disk spectra obtained with the NIRSPEC instrument on Keck II, in the M band - the location of the rovibrational CO emitted from the inner disk. Our sample of stars covers a wide range of stellar properties as well as properties of their associated disks. We assess CO as a tracer of inner disk gas, comparing to accretion tracers and outer disk gas tracers, and investigate its presence as a function of stellar and disk parameters. Additionally, we present a summary of results from LTE slab modeling: retrievals of CO temperatures, column densities and emitting areas. We assess the retrieval results to better understand inner disk conditions around a variety of stars.