Interesting to read people's thoughts on this. I know from a commercial point of view that sometimes a blue sky will win out if it's for some kind of tourist brochure. But for me, blue skies are just boring.
As a kid, I used to love drawing. As well, in my parents dining room there was a picture of Constable's The Haywain. I used to look at it for ages and even mistakenly thought, in my child's mind, that it was of Harnham's Old Mill near Salisbury. And what do you see in that picture? Moody skies!!!
Coming from Salisbury and having access to the Water Meadows that Constable used to paint from, it was kind of hard to ignore them. I used to spend many mornings there before going off to the office. My first image sale was of those meadows. Salisbury Cathedral, water meadows and sheep. Ideal material for a modern artist.