The first one's a little oversaturated but it looks nice. I like the composition with the mountains in the background in the right and the hill/grass on the left, but having the people in the middle makes it kind of hard to look at. If you had waited for them to be further to the right or more to the left it would have looked better IMO.
I like the second one also, but again its kind of oversaturated (meaning the colors are too strong, the grass too green and the sky is too blue, it looks weird).
The third and fourth ones are decent, but the shadow ruins them and is a big distraction.
The third one especially, the top of the mountain looks good, but hten having the bottom darker and gray makes it really weird looking and you can't look at it without focusing on that line between them.