The operation of nanoelectromechanical switches is investigated through simulation. A simple methodology based on a 1-D lumped model taking account of the Casimir effect is first proposed to determine a low-voltage actuation window for conventional cantilevers. Results show good agreement with 3-D simulation and prove to be helpful for systematic design. The conventional cantilever shape is then optimized to a cross-like design that is fully studied in a 3-D environment. Static and dynamic behaviors as well as effect of the oxide layer thickness are investigated with a view to suspended-gate single-electron transistor applications. The proposed structure successfully combines low actuation voltage and low power consumption, and it is shown that the switching speed is the limiting factor for the considered applications.