Linda, sorry to sound like a broken record. (Guess I'm really dating myself with that phrase, eh?)
I think the "Intro to Aikido" workshop idea sounds great; I still don't think that rules out the possibility that a woman's class might have value as well.
I feel like we have already listed some of the many reasons why women are (generally) under-represented in Aikido, but I can share my story to be specific...
Some of the things that made me personally reticent about getting on the mat for the first time: I have never been particularly athletic in the sense of playing team sports or anything of that nature. I have had weight issues my whole life and don't always feel comfortable with my body. I have a history of abuse which made me uncomfortable with the idea of all of that physical contact with a bunch of men whom I did not know. I was also not all too confident that the guys would want me there, and didn't know if I wanted to deal with that vibe. I did have a fear of getting hurt - but after I started practicing I also realized that perhaps the bigger fear was the fear of hurting someone else. (Nice girls don't punch, right? That's why my atemi sucks.) I was afraid that I would not be able to devote the time necessary because of my family responsibilities. And finally, I was just kind of afraid of looking like an idiot, especially at my age. A bunch of reasons, some gender-specific, some not.
For me, it really was not about the finger nails, or the fact that I look like the Stay Puft Marshmallow Man in my gi. (Which I kinda do.)
So... I managed to face all of those fears and realized that I could get up and go ahead and feel uncomfortable and scared, look like an idiot, feel guilty about leaving my kids for a couple of hours...and survive all of that to discover that I love every minute that I spend on the mat. I like sweating; I like how each partner makes the technique completely different; I like feeling my body move in ways it never has before; I love the excitement of lining up and wondering what we're going to do next. I love the little victories when I FINALLY "get" something that has eluded me for weeks or months. I love learning something totally new. I love that Aikido makes me feel like I want to be present, inhabiting my body. I like the way Aikido shows me that I always have many options available to me in the midst of challenges/confrontations.
So I guess I'd just like to share all of that with other women who might have a list of fears that looks something like mine. Not because I don't care about the people whose list of fears/obstacles is different from mine, but because I feel like maybe I am in a position to reach those particular women.
Maybe my first proselytizing mission will be to try to encourage some of the other dojo Moms to get out onto the mat with their kids. If they're going to sit and watch for an hour anyway, why not just join in? I know these women are already interested in Aikido because they've chosen to bring their kids.
THEN I will amass a great army of Aiki-Women-Warriors to fight evil and injustice throughout the world... and we can have our own anime series... and trading cards.