Personally, I was so curious to learn more about AXD, I couldn't find my pledging or initiation ceremonies boring! Was this girl just not into it? (Guess not, if she quit.)
The girls should really figure out for themselves what they believe. I could say "character and learning" should be their focus, but if it doesn't resonate with them, it won't help. And as for what's cool, well, they are planning on sticking around longer than five years, right? Cool doesn't last.
Some ideas:
-Delta Upsilon's rituals are open, so it might be worth talking to a DU.
-Flowers have traditional meanings, and theirs should represent something central to them. See
http://www.800florals.com/care/meaning.asp
But, cruel as this sounds - if they can't figure out what mythological stories they like, or find a Greek professor to help them out with words, I'm not sure they're ready to be doing this, or that they understand a sorority is about more than social fun.