I really like the first one, although the cropped foot only bothers me a tiny bit!
I love the big sister consoling the younger one! The lighting is a bit flat, but I think a soft light layer at low opacity in PS will take care of that.
The third one is cute, although I wish I could see what she was looking at...
The fourth one with the seagull: I think it would be easy enought to clone the gull out if you wanted to.
#1 - Adorable - love the expression. The cut-off foot is nagging at me when I look at it. Otherwise very nice. If I were feeling particularly edit-y I might take a few rust stains off the woodwork or lighten them, but that's just me.
#2 - Very cute. I might brighten their eyes a little, though. And, as stated, remove the white blob.
#3 - Like this one a lot. Maybe brighten up the eyes, though.
#4 - Also like this one very much. The bird doesn't bother me at all, but it could be moved further into the upper corner, if needed.
#5 - Great expression of childhood joy. Very nice. I might brighten her up a little, but I like the unusual setting.
#6 - It may be cliche, but it isn't to the parents. Nice shot.