Elizabeth Davis, a prominant midwife, has written a lot about Blood Mysteries. She has some great ideas about Menarche celebrations and why they are important to our daughters.http://www.elizabethdavis.com/mysteries.html
I think the most important part is that this is your DAUGHTER'S celebration, and so she should be the one to pick what happens. Suggest ideas of course, but you shouldn't force a public party on her anymore than you should ignore this special time in her life. The point is to make her moon a celebration of her womanhood, not a curse or something to be ashamed about. If she picks something special that she is comfortable with this will be a validation of her ability to have control over her own life now. It will also start off her relationship with her body in a positive way, instead of learning that her moon is dirty and she should hide it.
Some simple ideas to include:
Buy her a red shirt, dress, scarf, or other clothing item that she can wear every month when she bleeds.
Buy a red piece of jewelry for the same purpose, to wear every month when she is bleeding.
Eat red foods at the party!
Have a group of her friends and family members (women) tell the stories of their own menarche, good and bad. Have them share their favorite parts about their moons and why they are proud to be women.