Moderate Hiking for the 45+ Crowd

I know there are many hiking groups out there, but I still seem to end up on many waiting lists. I think the Denver, Boulder, Broomfield area needs another moderate hiking group. Our hikes will be 4 - 10 miles with 800' -2000' elevation gain. I'm still new to hiking in CO, so I will be doing many hikes for the first time. Feel free to suggest you favorite hikes for our group. Let's enjoy our beautiful CO mountains!