That is actually a topic I thought about quite a bit. Taking Skyrim as an example you have an interesting transition from relatively temperature stable caves and howling snowstorms outside. The idea of slightly frosted flagstones or something similar may be the way to go.
I also thought it may be good to just do what I did for my Dungeon Crawl stuff, as this would fit most scenarios:
I'll make them round and may go easy on the moss, but in general it should work for all kinds of environments.