I'll second Sulis' idea of hands-on bike maintenance. Wish I could get one of the LBSs around here to do a class on that.

Also, this might be an opportunity to get more women riding. If you have clubs in the area--and I'm sure you must--do they have sub-groups for new or slower riders? Maybe that could be one thing you advertise or try to promote interest in at the seminar. Have women sign up for an introductory ride and see how they like it. Anyway, that's what I'd do. I ride with the slower women at the back of the pack in the club I ride with, and we're always on the lookout for more women who might want to come out and try it.