We present the results of GMOS multi-spectroscopic observations of the  globular cluster systems (GCS) associated with a number of luminous early-type galaxies, and demonstrate the power of such analyses for the determination of galaxy halo dynamics and the inferences for galaxy formation and merger histories.  A recent analytic development, exemplified by our study of the GCS in NGC 3923 (an E4-5 galaxy at a redshift of ~1700 km/sec) allows us to extract the spectrum of the diffuse light of the host galaxy from the same slitlets used for the the globular cluster (GC) targets. This facilitates the investigation of the kinematics and stellar population of the galaxy halo at radii much greater than usually probed in longslit studies.  In NGC 3923 in particular, we find  that there is no significant rotation in either of the 'red' or 'blue' subpopulations of GCs; the galaxy itself seems likewise to have no significant rotation signature.  We will describe recent findings in a number of target galaxies.