I'd find it hard to believe that creaky voice (/ vocal fry) is mainly an affectation *nowadays*. Being a transplant to California from New England to Southern California, it's something I notice constantly. I spend a considerable amount of time in places like coffeeshops, overhearing conversations of people below age 25. The thing I hear most is the glide up at the end of phrases -- which I find irritating, I suppose, because it is just not "music to my ears" in the way that tones from my region and generation would sound like. That is, I feel surrounded by these "strange Southern California people"! In the end though, it's just regional speech.

Closely following the up-glide is the creaky voice. It is so common and seemingly unconscious that I don't see it as an affectation. And it no longer has anything to do with "valley girls." I don't even think it has much to do with sounding cool or what have you -- though certainly it indicates one's age pretty well. I think it's pervasive enough to be considered, again, mainly a regional and generational thing now.

I have supposed that women do it more because they want to talk in a lower register, and their voices "bottom out."

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For Canadians who think that Canadians don't generally say out/about differently than Americans... sorry, but they most certainly do. I'd say it's the number 1 speech clue, from the American perspective, that someone is from Canada. It has become a bit of a custom to signify that difference with the orthography "oot." No, it does not rhyme with "boot." That's just the way the spelling has evolved. Regardless, there is a *very* consistent difference between how Americans and Canadians tend to say "out." Not all Canadians say "out" the same! BUT a really large number say it in a way that most Americans do not, and for that reason the difference serves as a good accent "border" between the two countries' speech.

Other aspects of Canadian accents are fairly clear, but these turn up in some American accents, too, such that they don't create such a perception of difference as does "out."