Nano- and microstructured layered films can serve as thermal insulators by minimizing continuous contact area, maximizing phonon scattering in the bulk, and introducing interfacial thermal resistances. Unlike commonly used insulators that consist of porous, fibrous, netted, and aerogel (nanoporous) materials and are often mechanically weak, nano- and microstructured layered films can show superior mechanical stiffness and strength. In this work, I compare two types of thermal insulators for different vacuum applications: 1) microfabricated films with highly controlled geometry and 2) stacks of coated polymer films. The microfabricated insulators are nanolaminate alumina-hafnia electrode spacer films for thermionic energy conversion cells. The second systems consist of robust flexible layered alumina-coated Mylar films for electronic and habitat insulation on the Moon. The electrode spacer films were made to withstand high temperatures (>1000°C) and moderate stresses (<0.5 MPa), while the layered insulation was produced to be more scalable and withstand moderate temperatures (<120°C) and high stresses (>20 MPa). The objective of this work is to identify the dominant determinants of heat transfer in layered systems, from architectural, bulk, and surface effects. As part of these studies, I experimentally measured thermal resistance and effective thermal conductivity as a function of applied load for films with variable macroarchitecture and bulk properties. In the electrode spacer films, the architecture and surface better mitigate heat transfer compared to the bulk. In the layered insulation systems, heat transfer is also controlled by the interfaces, with effective thermal conductivity down to 2.5 mW/mK in high-vacuum.