What kind of riding do you do and like?
Long road rides over passes?
In CO, you can have any and all of the above.
There are literally 100's of possible rides,
A new easier ride would be the Rio Grande Trail from Glenwood Springs to Aspen and return - 88 miles total.
Or, the Glenwood Canyon Trail along the Colorado River - about 35 miles round trip.
All of Summit and Eagle Counties have stupendous bike trails, including over Vail Pass, through Breckenridge, Frisco, Keystone, etc.
An excellent and challenging road ride os the Copper Triangle - through Leadville, Copper Mountain, Vail, etc. 3 high passes.
Lots and lots of mtn biking.
The Denver Metro Area has over 600 miles of cement trails - you can go 40 miles without ever crossing a vehicle road, generally along creeks and the Platte River.
See this thread for some pistures of the above.
Annual 50+ Bike Forum Ride?
Tell us more.