Unfortunately this looks a lot like a snapshot. I'm not sure if the alone is the adult amongst the kids or the group alone looking at the city. Too bad it's not that clear a day. Good composition.
If you have photoshop, you should try to use the Save for Web feature, it will let you set the image file size and pixel size. Here is a tutorial on DPC to walk you through it. I hope this helps you. I saw you got your image up to the max file size but had to make it small. This is because it still has exif data attached to it that tells you this was shot with a D80 and all your settings. What the Save for Web feature does is get rid of that data and allows more of the file size to be used in image quality. Hope this helps
Great idea. I think I would have tried to have only one person (actually alone) in the shot to emphasize the spirit of this challenge. Also I might have cropped in closer for a stronger juxtaposition of the person & the city.