Flower girl dress question

What length is your flower girl dress going to be? I have two flower girls who will be 4 & 6, one of them is pretty tall and skinny. I saw a dress I love online but it's an ankle length dress. I'm not sure what to do, if their dress isn't full length, I'm worried their tights and shoes won't match exactly and will looks funny.

What's everyone else doing? Thanks!

Edited because I'm the worst Aunt in the world and said my niece will be 7 instead of 6 years old!

if it helps at all i had a similiar question and i called the store im ordering my flower girl dresses from. i went to
http://flowergirlprincess.com

They have dress measurements for all their styles. The Length measurement goes from the seam in the shoulder to the bottom of the hem. in my oppinion this is the most important measurement because the sash around the waist can adjust and slack in the waist just as long as you go a bit big.

http://flowergirlprincess.com