I would add that subsurface scattering shows up a lot more with Ray Traced lighting on and at least at medium because what the setting does is scatter light on skin surfaces and some transparent textures -- like the edges of clothes, cotton, or curtains. It's the effect when you shine a flashlight under your finger, and you make your finger glow around the edges, and at the soft points where light will leak or scatter through. If you don't care if skin has that glow to it, turn it off.
In fact a lot of the base settings don't really show up well if ray tracing isn't enabled. Fog and Clouds still look very low quality even on ultra when shadows pass through them, so stick to medium or lower for those. The only time I saw real effect with them on ultra was backing my car up in reverse with ray tracing on; the gas from the tailpipe and any fog the car ran into popped really nice. A lot of these effects are just shallow without ray tracing, and they are so GPU intensive. The difference in the game between medium and high settings is honestly disappointing for PC.
The only reason I don't go back to playing on the Series X is I love ray tracing, and with the settings tweaked just right on a rtx 2080 super, I can get just above 45 fps average and a peak of 59 fps. With Gsync on, that flux doesn't even feel like less than 60 fps as long as I don't break 40 fps downwards.
*Edit: Thank you for this post btw. I agree it was very informative.