When I first came back to CO in 2002, I got back into fly fishing... Deep. I did a few exibitions on fly tying and rod building for the shop I frequented weekly, Alpine Anglers in Aurora. It's closed down now sadly. Living in Castle Rock, I would go up to Deckers and Cheeseman Canyon regularly fishing. I also fished Spinny Mile (the Dream Stream) and Eleven Mile a lot. Grew up in Ft collins and Greeley, so I would take a trip or two up to the Big Tom every summer too. Went a few other places along the way too, but I fished the South Platte hard. I had a lot of 50+ fish days, all catch-and-release. Taught more than a few along the way. I taught my step-daughter how to fly fish when she was 10.
If you are fishing moving water here in CO for trout, there is only one way to do it right IMO, fly fishing nymph patterns. Top water and streamers will work sometimes if the conditions are right, but here in CO the bugs are small and plentiful. Nymphing is an art and once you get it down, you won't want to see a lake ever again.