Carbon monofluoride (CF)(n) and graphane are two very different materials from the practical point of view, but the basic chemical motifs of these materials are closely related both can be described as two-dimensional polycyclic (fluoro-/hydro-)carbons. However, the actual experimental data on the structure of these materials is ambiguous ((CF)(n)) or scarce (graphane). Herein, we report a detailed computational study of structure of (CF)(n) and graphane, both in a monolayer configuration and in three-dimensional stacked arrangements. A crucial point in achieving a proper description of layer interactions is the use of a nonlocal density functional to describe long-range dispersion attraction from first principles. We find strong qualitative and quantitative similarities between the two materials in both conformational energetics (including a "gauche-chair" conformational motif not considered in previous studies) and layer stacking arrangements. A molecular mechanics force field is derived for (CF)(n) that performs exceptionally well at reproducing our quantum chemical results and fits into a very general OPLS/AA molecular mechanics framework. The combined results of quantum chemical calculations and classical molecular dynamics simulations using the new force field suggest a pathway to explain the too-small experimental in-plane lattice constant values observed in these materials, as well as the variation of interlayer distance in (CF)(n), on the common basis of conformational disorder.