Rocky Mountain National Park is a must see. Be sure and drive the "Old Fall River Road" up to the Alpine visitors center. The drive, however, is not for those who don't like steep grades and fantastic views. It is a "one way", dirt road to the top of the mountain range. The town of Estes Park, which is at the east entrance to the park, is a great place to also spend some time. As a matter of fact, my wife and I are leaving today to spend a couple of weeks out in Colorado, and one of those weeks will be in Estes Park. We love it there.