I don't shave my legs, but I do shave my underarms at the moment. I wish I didn't and now at the prospect of having a little girl in a few months, I am seriously considering letting it grow out like I planned to when I have children. Thanks for reminding me.
I think it's important that you have men in your life understand that they aren't to make negative comments to your DD about it. When I was 12, my dad looked over at my legs (which had never been shaved) and said, "god, when's the last time you shaved your legs" and I cried and my mom initiated the shaving ritual which I did for 4 years before calling B.S. (I also started shaving my armpits for a similar reason with another family member who was "disgusted" by the 4 wisps of hair growing under there when I was 10.
I am lucky in part because DH's sister (who will be our children's only aunt, and I'm sure the "cool aunt") doesn't shave at all, so there will be more than 1 female role model for any child we have.
I agree that your SIL will be a good example to have for your daughter and I also agree that having the men and boys in our girls lives being positive about this issue is important.