I've ended up watching it a few times during this holiday season - I love the character of Amy....she's definitely one of the more interesting ones and I like the growth we see in her.
On a side note: I love the outfit she's wearing in the first scene we see her in - I think it's a black t-shirt with red skirt and black tights/leggings
You can kind of see it here:
Photos from The Family Stone
And I really loved her hair in this movie