I think that your idea to use selective saturation was a good one. You've really managed to capture the emotion and excitement of the children wanting to go in the pool. Perhaps if you had chosen to selectively saturate the water in the pool instead of (or in addition to) the bathing suits you might have been even more pleased with the results.
The de-sat and the colors remaining are too harsh for my taste. I think de-sat works best on just one or two main focal points in an image. It is a great reminder of summer days, but appears a bit like a snapshot or too busy to be in a calendar. All this simply an opinion.
It could be just my monitor but the pink straps on the girls bathing suit and the boys snorkle seem to bright. other than that it is a very pleasant photo..