I've decided to not downplay all this, but instead try to model how to respond to her getting so much verbal attention from strangers. Afterall, when she's older, she'll have to respond all by herself, without me there.
You could try: 'Yes, I think it's her warm smile that makes her so beautiful.'or
'Yes, I always find a person attractive when they have that look of persistince on their face.'
A la Rimm, you can turn a comment about a 'feature' into a comment about 'character.'
Afterall, even if your dd grows up to be physically attractive, she is surely going to go through an 'ugly duckling' phase somewhere in the process.
My .02,
Grinity