I have settled on using five inch hexes for my Napoleonic wargames and have been slowly building terrain features. The biggest challenge has been buildings, which need to look vaguely in scale, but of a size that will allow a unit to fit within the hex. So far I built a walled farm, a larger farm/chateau, and my latest is a church, with wall. This will make a useful strong defensive position:
It is made from foam board, balsa and card and painted with DIY sample pot paint. Here is the same building with an infantry unit within the walls:
My infantry units are 12 figures on four bases. It will also accommodate a gun battery on one of my standard artillery bases:
The next terrain project will be a two or three house village.