I have assisted several ladies in getting the right bike for them. Understanding what makes them feel safer and happy on the bike is key to keeping them riding with you. Besides what has been mentioned The HD Slim is a low seated bike with lots of torque when needed off the line and feel easy to me in the curves.
But for the best bang for the buck, I think the Japanese cruisers are sure to work. The Kawasaki 900 is quite the fun little bike. And remember, any bike can be ridden fast, even the little 250s. One of my friend's wife will not ride her 2002 LS 650 Savage because she thinks it is too fast for her. She is a short lady, I'm guess 5'2' and not heavy at all. I have ridden her bike and find it to be a fun machine, especially for a low weight person. The newer bikes are now called Boulevard S-40. These are not costly and quite reliable. Seat height is good as is lower center of gravity I say.
, she ended up with an 883 Superlow, and the plan was to eventually get a Fatboy low.
