I LOVE the striped leggings!! But I agree that the shoes seem so plain compared to the rest of her adorable outfit! I like putting little girls in Mary Janes and Converse All Stars, depending on their personality.
I also think the girl on the I Can Read cover is awesome! Her expression is wonderful, and I love her hair!
Another thing with dresses is that it's quite common for little girls to have either A-line dresses (which is essentially what you have here), or an empire waist. I love doing the empire waists because I find it adds a lot of visual interest, and I love playing around with how the dress hangs with folds and ruffles.
I think older girls (tween and up) have styles that involve more layering. Skirts and knee-length leggings, or skinny jeans and slouched boots or high tops with big tongues or ballet flats, longer shirts with a shorter shrug or sweater or jacket, etc...at least that's what I see with the girls I know of that age.
I try not to get too trendy when I design outfits, as I don't want stuff to look too dated down the road, but I do like putting lots of personality into their outfits, so it seems more like a personal style than a current trend.