I was born and raised in northern Colorado, and I cant give you too much information on the south Platte river, other than Cheeseman Canyon is blast to fish.
I will say that the north Platte running out of north park near Walden and then all the way into Wyoming through the Miracle Mile and Grey reef sections might be the single greatest trout river in the continental US. Estimates last year at grey reef were at about 5000 trout per mile of river
