I prefer my Witcher games to have a grey, grizzled, gritty feel to them. I also couldn't stand the default 60 FOV, especially with my ultrawide monitor. And I absolutely detested the sickly blue fog that they put in the distance for absolutely no reason (pro tip: stuff still gets rendered behind the fog, so the fog doesn't improve performance.)
So I downloaded a mod to increase the FOV and another mod to remove that ghastly blue fog. I then used SweetFX to desaturate the living hell out of everything as well as reduce the exposure and add a hefty amount of film grain.
Here's what it looks like (and for bonus points, open the two screenshots in their own browser tab [so the image is bigger] and flip between them to see the difference!)
Now here's the same picture without SweetFX or fog removal, though with the same FOV:
And finally, the same as above but with vanilla FOV: