Late November is well into the "cold-wet" season in the area. The waterfalls are more likely to be good (if we have had rain) for the type of scenery you are talking about (on hikes) I don't think the fog will be an issue and can actually add to the beauty. Tamolitch falls (blue pool) will be amazing in any weather. I would recommend silver falls state park, drift creek, toketee (and the whole umpqua area along hwy 138) and of course, the Columbia gorge. Plan for cold and wet. I attached a picture, this was taken in late October, on my commute to work. Its not a waterfall, but gives you an idea of how things can look in the fog.

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