Who else is going? I read you have a 15yo son who is helping planning for the younger ones? I'm guessing the other young ones are boys. Going with that information are you planning to seperate and spend time just with her? My DD is 12 and would not like the BBB experience - as a tween she would be more embarassed that mom signed her up for something she would think "babyish" and this a girl that LOVES her glitter! I wouldn't classify her as a girly girl but she likes her sparkle

If she did the pirate thing would it be only her, would she rather be with the rest of the group? Just thinking that you could do things that highlight her experience but don't segregate her from the group... she's at WDW afterall and I'm sure she's gonna have an amazing experience without the "extras." What resort are you staying at? Does it have a spa where you could do a manicure/pedicure with her?
That being said, the pick a pearl thing is special to just her, also if she has or likes any jewerly at all you might want to consider purchasing a pandora style (does not have to be pandora name - there are chamilia, and others but people seem to be more familiar with the pandora name) bracelet for her and start a memory bracelet. Something she can add on to as she grows and goes different places. Or WDW also has themed Alex & Ani bracelets - just a special souvenier she would always have.
On that same line, pressed pennies are a great thing to do and not outrageously expensive although over time it add up. Check this out:
http://www.bing.com/images/search?q...7F5D73B9542705AC85A209CEF59BD96BC&FORM=IQFRBA
I agree with the character meals as well. I wouldn't over do them but throw 1 or 2 in there with a variety of characters.
Have fun!