I'd split into documentary-reproducing what you could witness and artistic-using photographic techniques to create a pleasing result. It's also not really post

I'd split into documentary-reproducing what you could witness and artistic-using photographic techniques to create a pleasing result. It's also not really post-processing - it's a choice you make at capture time. Do I leave the shutter open for (say) 1/30s to document what I'm seeing, or 5s to capture the light trails?