oh cool - I'm glad I popped back in - Thanks for the shots!!
I'm a bit in critique mode here so I'm going to tell you what I think and what I might have also tried on these 3.
I'll start with number 3 because I think it's the strongest of the 3 - and remember this is just what I see, in an effort to help you understand what a 'random viewer sees'
Number 3 - the technicalities are all strong, exposure and tone/colour on the subjects are spot on, background also - but there's a problem with that viewing platform (?) at left and the logs or rocks there too, also you have the horizon running through their heads, with distracts in my opinion.
What you could have done is lay right down on the ground - further than you were already, and shot with their heads into the sky a touch more and you probably would have lost the platform too. One other thing I would have definitely done was take them into the marvelous field down yonder.... that looks like the spot to me!
Number 2 - again pretty good, but missing on a few things - the white of the shirts is lost in the white of the sky - meter the light blue sky and in this instance, set your max synch speed for your flash and then drop the exposure on it by a half a stop by adjusting (closing) your aperture (you'll find yourself around f16 or 22 at 1/200th I would guess). I would think then your flash settings would be about right.
Now the first one has the most potential due to the nature of the shot - it appeals to me, and will appeal to the client too, but again the white side of the frame makes it feel unbalanced - also I think the words at the bottom are too tightly cropped in this instance. So what would I have tried? I think this one is dying to be high keyed - forget the flash on this one, wait - did I say that??

expose the kids properly, and blow he background right out, also I'd probably try with them sitting on one end of the wording, looking away or mischievous or something - just to take away the centre heavy framing..... - you may need the flash to expose the wording actually......

That's just my take on the three I see, I don't mean it as a put down at all, just trying to help from an objective point of view.
Oh, there's also something on the top left of the frame on number 2 (and I just realised that 'field' may well be marshes and swamp