Will you be my bridesmaid?

Beginning in the spring before we were engaged, when I thought about how I was going to ask my closest friends (and my only sister) to be a wedding attendant, it often made me anxious and excited at the same time. I wanted to be able to include many of my closest friends, but I knew that it would be difficult organizing everyone and I'd have no friends left to watch the ceremony! I waffled between 6, 7, and 8 bridesmaids and thought about how pictures would turn out with each number, who would do what, how'd they get along, etc. Then my mother told me that Filipino weddings have a few more wedding attendants than other kinds of weddings:

1) Primary Sponsors - basically same as the couple's wedding godparents.
2) Secondary Sponsors - for the cord (to bind us), candle (to light our ways), and veil (to clothe us)
3) Bridesmaids and Groomsmen
4) Ushers and Usherettes
5) Flower Girl(s), Ring Bearer, and Coin Bearer (the coins are a Spanish tradition, I believe)

This gave me a little more flexibility, but it was still difficult to decide. And then, HOW do I ask them? I wanted to do something a little extra to show the girls that I really appreciate my special relationship with each one of them rather than just asking them in person or over the phone. Also, since not one of them lives in the same city as I, it was a little more difficult (they're in NY, PA, my hometown, Richmond, and my sister is in London). So, I decided to write them a letter thanking them for all their love and support and friendship and begin decorating a scrapbook for each one. I've asked them to send back their responses on the scrapbook pages that I'll save as a memento of our experiences together. Below is a shot I took in my prep stage:The notecards aren't attached to the page and the girls are free to use them or use something else when they respond.

I've asked all the girls to call me before they respond because I want to make sure they understand what goes into being a bridesmaid (I'm the first of our friends to walk down the aisle) and I want them to be there with me in any way they can, bridesmaid or not. I would never want any of them to feel like they have to be one or be surprised at some of the duties associated with it. Did anyone else do something specific or have something important in mind when "making the ask"?