K.F.
I love sleepovers. You get to see, meet and learn her friends. Activities for a party or sleep over could include a scavenger hunt. What are your daughter's favorite activities or favorite movies or television show? You can theme the scavenger hunt around these things. Since your girl isn't a girly girl, you have so many more options for the fun. If you daughter is into drama or dancing you can add elements of acting and dancing.
What ever you do make it fun by being creative and thinking outside the box?
You could have the girls make a movie, do a who-dun-it, or just went to a party this weekend for a 12 year old boy. They had three different video game systems running in three different rooms and basketball in the back. Seemed chaotic to me but my boys had a blasts. The birthday boy's girl guests were playing the Wii in the livingroom.