This work presents a design space exploration for electrified aircraft that use electrical components for propulsion, and identifies configurations and missions for which electrification can provide an energy-usage advantage relative to hydrocarbon-based propulsion. A framework was developed to capture the major trade-offs of electrification at cruise condition, as well as the effects of distributed propulsion and boundary layer ingestion. The analysis is based on a parametric exploration of the trade-space with focus on mission size (payload and range) and technology level. It considers aircraft classes ranging from a 20-passenger thin-haul up to a twin-aisle intercontinental transport. All-electric aircraft are found to be best at low ranges (200–500 nmi), requiring the lowest amount of on-board energy but with a limited feasibility region. Turbo-electric architectures can be beneficial even with current technology, and are best for long missions. Adding a turbo-generator to an electric aircraft, for a hybrid-electric propulsion system, acts as a range extender and is optimal for intermediate-size missions. Finally, leveraging distributed propulsion and boundary layer ingestion improves energy efficiency and expands the range of feasible missions for highly electrified aircraft.