In the Springs, Cheyenne Mountain State Park is a good bet--lots of trails there for all difficulty levels. A newb can string together a nice ride with nothing overly technical. There's also crazy good scenery and mostly smooth trails in the Red Rock Canyon open space right in town.
It sounds like Rampart Reservoir was custom made for you. 14 miles at altitude, mostly smooth, roller coaster cross country stuff (a couple mandatory dismounts) with killer views of Pikes Peak.
Near Denver, Centennial Cone should fit the bill--great views of a dramatic canyon, good mileage and nothing more technical than a couple tight switchbacks.
Alderfer/Three Sisters Park is also a nice place without a lot of tech.
The trails around Kenosha Pass are gorgeous and will get your heart rate up, but not throw a lot of tech at you in the process--Kenosha to Georgia Pass is a Colorado Classic.
The real classic within about 1.5 hrs of either the Springs or Denver is Buffalo Creek. #1 here on singletracks--you can really get in some miles, and the scenery is great. It's a huge network and you can customize a ride to your liking. Other than a couple trails, most of the place is nice and smooth. For a place to be so highly regarded in spite of being mostly non-technical should tell you something about the quality of the riding there