Most people in Colorado seem to get into mountineering through the states 14,000' peaks, the majority of which are "walk up" mountains with trails. There are alternate routes on those peaks, some of which provide some good scrambling opportunities or technical climbs. Those routes have the added benefit of being "less traveled" and you are not too likely to see other climbers until the summit.
As for the hidden gems, the "best" scrambles in the state. I guess we are all a little selfish here. Many of us "cut our teeth" so to speak on the 14ers and want to keep the crowds away from the scrambling gems. If quality scrambling and not altitude are your objectives, head to the Indian Peaks, Gore, Elk, or several of the San Juan subranges like the Grenadier, Needles or Sneffels ranges. You will find an abundance of great fun to be had, and less crowds.
There is a book called "Colorado Scrambles" by Dave Cooper that has 50 such suggestions, 14er and non-14er, all over the state. Its a good starting off point for finding the good stuff to be sure! Many of the peaks in that book have neighbors with equally as good scrambling opportunities.
There are some lists already on SP as well that touch on classic scrambles and 5th class routes: