The structure, elastic properties, thermal expansion, and thermal conductivity of the orthorhombic-structured A(3+)B(3+)O(3) perovskites are determined using atomistic simulations with classical potentials. When considered as pseudo-cubic monoclinic systems, they show relatively small deviations in structure and properties from their cubic perovskite parent phase. The variations in properties are shown to be related to the magnitude of the tilting of the BO6 octahedra, which in turn is related to the relative sizes of the A and B ions, as encapsulated in the tolerance factor.