AnonymousHard to pick just one. They’ve all got their own strengths (pun!).
Like you pointed outust one or two women growing gives writer and reader a chance to focus on their personal feelings, and how they handle the change in their lives, and those around them. Also, we get to see how their outlooks change: from "oh, no, I’m a freak!" to "hey, this sure is handy moving things around the house," to "better hand over my pocketbook, the mugger’s stronger… than… I used to be!" to "All this, and love, respect, brains and beauty, too. Life is good."
Of course, I wouldn’t mind seeing the flip side of this… at first the woman thinks "Yes! Time to kick butt and take names!" to seeing the hassles, big food and clothing bills, to friends, family and sweethearts switching steadily from love to fear of her, and that witchy rival of hers trying to horn in on her secret, until she finally decides getting big wasn’t worth it.
Which leads to… a select few getting it. This gives us a little more insight on how different personalities handle getting muscular. Some may love it, some might not. Some turn into harpies, some may become motherly guardians. This is great for where cliques form, like in high school or the workplace, and gives us a cross section of a society without being too overwhelming.
We also get to see what happens when two different types with extra strength meet. Catfight of the Titans, anyone?
Then some take on the challenge of powering up all the non-Y chromosomes. This is great for totally seeing how humanity as a whole, different world cultures, economies, political structures, and other institutions handle it. Also it’s good for those that wonder, "What would the world be like if women ruled it?"
And if it’s instantaneous, it makes for some good panic-in-the-streets scenes. 😈
Each of the three scenarios are good, so I can’t pick one easily. So… why not go for ’em all? Start with just one woman getting the secret, and the muscles, then slowly she shares with a few trusted friends, or it leaks out. Then it spreads out steadily over the neighborhood, the town, through the state… and so on until it’s Planet Amazon (and I don’t mean the shopping website).