By default landclass is defined as grid data within FSX, so that means that for each area of roughly 1.2 x 1.2 kilometre you can define what kind of land usage it has. For some time already I wanted to test what effect landclass polygons would have on the looks of the terrain, so this morning I gave it a try.
I had some land usage data for the Netherlands available, which gives the type of land usage as vector polygons. So I wrote a quite translation tool to map those values on FSX landclass GUIDs. Below is a screenshot of the results in FSX. As you can see more detail becomes visible in the terrain, like smaller forest areas, dunes and beaches. Also towns and cities appear clearer at the location where they are in real world.
In the screenshot you can also see that the mapping is not always perfect yet (for example the dunes became sand as well), but for a quick sunday morning experiment I am quite happy with the results. If I could find some land usage data I could use freely (unfortunately that is not the case with the data I used in this test case), then this could be an interesting approach to make the terrain more recognisable without using huge aerial imagery.