I wanted to write a short note about using warp and liquify for perspective corrections for landscape photography because I haven't seen much said or written about this except the occasional person that will use this to de-fish (personally I think it is usually preferable to a full blown correction). So I have the impression that many people do not even think about using them for landscapes.
But I wanted to give a couple of examples where I took an image at a wide-angle FL and ended up with some weirdness that I could not correct with a distortion correction. In fact the second example was shot with a TS-E, so I didn't even have to point the lens down. Also note, that these have nothing to do with buildings or even trees, but they are common with water bodies for some reason, often, but not always looking down on them.
So in these cases I find the warp and liquify (with a large brush), useful. Either individually or first warp, then fine-tune with liquify. Now of course, you will lose some sharpness, especially where you are stretching the image. You should watch out for that, and it may become a factor in where and by how much you manipulate the image, but in general I find the distortion more objectionable.
So, example #1. I took this a 12mm on a crop, hiking up a trail. I got some rocks in the foreground and just wanted a pic of the valley. When I got to looking at it though, the sinuous stream which is on a basically flat piece of land looked like it was sloping heavily to the left. Also the mountain range looked kind of sloping that way too. I tried rotating the image, but then of course all the clouds looked wrong.
So this is what the image looked like pre-warp:
Now you can go nuts trying to get everything 100%. I don't think I got this perfect, but to my eye it looks better (you might have to download the images and flick back and fourth to see all the adjustments). But IMO it does look more even and balanced. Some of this may be perspective, some lighting or optical illusion due to the foreground, or for the mountains, just the way they are.
Of course, I understand if folks are concerned about altering the 'reality' of what was in front of the lens. But we certainly don't see at a 12mm focal length, so while some of the corrections are 'altering reality', my opinion is that the result is much more the impression of the actual view.