African easterly waves (AEWs) are known precursors to tropical cyclone (TC) formation, although it is not always clear which AEWs will develop and which AEWs will not. To investigate AEW evolution, this study examines novel observations from the geostationary Advanced Baseline Imager (ABI) during July-September 2019. Case studies are conducted for two AEWs: one that became Hurricane Dorian, the strongest and most devastating hurricane of the 2019 Atlantic hurricane season, and a long-lived September AEW that did not become a TC. Lower-level moisture and flow, and the strength and spatial distribution of convective activity, differed between these two waves. By then exploring these characteristics for additional developing and non-developing AEWs, ABI observations show that developing AEWs are associated with low-level moist air ahead of the wave combined with enhanced convective activity, while non-developing AEWs tend to encounter drier air and exhibit a persistently broader structure with less-organized convection.