Thats a great idea and the photos look fantastic indeed,
fortunately i also know some of them here from the forums in big size

Its nice that you picked quite manifold motives in different moods, makes the overall impression very special.
What i noticed after reading the "too much of that, too little of that" passage is that many of them are photos of trees.
But i just cant advise you to put one of them back because they look too good and each deserved to be on it as they contain a different atmosphere

Im not an expert on the technical stuff for such a copy store,
but from my sisters photos i know that the people in there can usually tell you in advance what they need and how it will look like.
Of course one pays a good amount of money for it, but still its quite amazing how high the quality of these prints is!!!