Folks, I have three areas of Colorado that we could base the trip from:

Central City/Black Hawk
Attractions:
- Rocky Mountain National Park
- Mt Evans Highway (14,264' high!) - Paved all the way to the top!
- Georgetown Loop - Ride the Historic Georgetown Loop Railroad :: Mountain Train Rides & Family Activities Denver Colorado
- Plenty of twisty road routes

Colorado Springs
Attractions:
- Pikes Peak/Manitou Springs - Drive or cog railway - Highway to top is only partially paved
- Caņon City - Royal Gorge - Railroad trip/Buckskin Joe's
- Bishop Castle - Bishop Castle, Wetmore, Colorado
- Cripple Creek/Victor - Gold tour
- Garden of the Gods
- Air Force Academy
- Flying W Ranch http://www.flyingw.com/

Western Slope - Durango
Attractions:
- Mesa Verde - http://www.nps.gov/meve/index.htm
- Million Dollar Highway
- Black Canyon of the Gunnison NP - http://www.nps.gov/blca/index.htm
- Four Corners
- Colorado National Monument - http://www.nps.gov/colm/index.htm
- Telluride/Ouray
- Durango-Silverton Railroad - http://www.durangotrain.com
- Monument Valley
- Great Sand Dunes National Park - http://www.nps.gov/grsa/index.htm