Your niece is a cute little girl! I like her expression in the first one (she looks happier). I'd crop it a bit from the left so she's not so centered and cut out the spots on the floor behind her. Some people wouldn't like the strand of hair in her right eye. Since she's a little girl this might be normal for her and you might like it.
On the second, while she's in focus, her expression seems to say that she doesn't like being photographed. (maybe you like this!) I sure get these expressions out of my kids a lot! But it could be typical of her. I also find that the white door, because it has more light on it than her face, is distracting. It might be stronger if it was cropped out as much as possible.
