Large Eddy Simulation (LES) of shear flows driven by Kelvin-Helmholtz instabilities such as mixing layers, wakes, and jets is of great interest because of their crucial role in many practical applications. The Monotone Integrated LES (MILES) approach is motivated here for these studies, and the basic components involved in a typical MILES jet model are described. Examples from MILES jet studies are used to address major aspects of transition to turbulence from laminar conditions at the nozzle exit including, the occurrence of global instabilities, complex three-dimensional vorticity geometries, and their impact on jet entrainment. Quantitative analysis of the small-scale features of the transitioning simulated jets is presented, and convergence issues are addressed in this context.