I had never been to Centennial Cone before for anything.  This is truly a beautiful ride.  It is one very big loop, maybe about 10 miles.  We made it in 4 hours with breaks totaling probably 20 minutes.  We trotted at least a third of the time.  The views are amazing to Denver, the North side of Evergreen, Chief Hosa, and of course the mountains surrounding and to the West.  We passed maybe 15 bikers, who for the most part, were horse friendly.  Didn't see any hikers.  On the weekend there are alternating hiking/horse and biking days.  See their website for the schedule.  There are not any spots to water your horses, so bring your own to the ride - you will all be thirsty when you get back to the trailer!  The trail traverses around the Centennial Cone, so some parts are flat, some up and some down.  A great variation.  Beautiful terrain, vistas and flowers.  Pictures on the website.  Next ride at Pine Valley Ranch - August 18th.