Balance-of-plant design aspects of two inertial fusion energy (IFE) reactor concepts - the laser-driven SOMBRERO and the heavy ion beam (HIB) driven OSIRIS - are being evaluated at a preconceptual level. The net electrical output of both plants is selected as 1,000 MWe (reference case). The economics of higher and lower capacities are also being evaluated. The heat transport system for both the reactors utilizes an intermediate loop with liquid lead as the intermediate coolant. An intermediate loop is chosen to reduce the potential of tritium migration to the environment. Both reactors utilize a supercritical pressure steam power conversion system with double reheat to achieve high conversion efficiency; a high efficiency is critical due to the capital-intensive nature of the plants and the low efficiencies of the laser and HIB drivers. The SOMBRERO plant facility is characterized by a large reactor building dictated by the laser optics configuration requirements. The plant also includes two moderate-size laser buildings. The OSIRIS plant facility is characterized by a moderate size reactor building, whose size is dictated by the remote maintenance requirements. In addition, a five-kilometer-long HIB tunnel is a unique feature of this plant. A remote maintenance approach is proposed for each of the reactors consistent with state-of-the-art methods and tools.