One of my favorite places to visit in Colorado is in the western part of the state, just south of the I-70 freeway and city of Colorado Springs. Colorado National Monument contains some beautiful red sandstone rock, with massive canyons, some unusual rock formations, and desert vegetation dominated by juniper and pinion pines. There's a beautiful drive (Rim Rock Drive) along the plateau's rim, offering many places to park and enjoy grand vistas of the Monument and, in the distance, Colorado Springs.
There are a number of hiking opportunities in the monument and folks love riding their bikes and motorcycles along the canyon road. If you're lucky, you might spot some wildlife like desert bighorn sheep and golden eagles. Definitely worth a half day of your time if you're traveling in the area.