I'm not sure what you're into, but Shipshewana, Indiana is a fun girls weekend. They have a lot of shopping, hand made Amish products and opportunities to do arts and crafts yourself. They have special Christmas activities this time of year too.
I spent a weekend at Frankenmuth last year and there was a lot more to do than several years ago. They have a new River Place mall that has fun stuff going on and the karaoke at the Bavarian Inn is fun too. They have a laser light show every night. You probably won't be able to get a room at the Bavarian Inn this time of year though.
I know people who've been to South Haven in the summer.. not sure how much there is to do in the fall/winter though.
Wheel's Inn in Sarnia is supposed to be a lot of fun. I've been wanting to go there for a while. Here's a link for that:
Wheel's Inn
That's the best I can think of!
Dee