Some of these will take a day, but most can be done in an afternoon.
1. Stroll the lovely Pearl Street Mall in Boulder
2. Have brunch at the Dushanbe Teahouse, an ornate gift from Tajikistan
3. Wander through Chautauqua Park and enjoy a scenic sunset at the Chautauqua Dining Hall
4. Drive up Flagstaff Mountain or hike into The Flatirons
5. Tour the Celestial Seasonings Tea Factory
6. Explore interactive exhibits at the National Center for Atmospheric Research (NCAR)
7. Picnic at Eldorado Canyon State Park
8. Hike, raft, or zip-line through the Rocky Mountains
9. Drive along Trail Ridge Road, the highest continuous motorway in the country
10. Ride the aerial tram to breathtaking views of Estes Park
11. Feel the flutters at the Butterfly Pavilion
12. See wildlife in a natural habitat at the Wild Animal Sanctuary
13. Watch a movie at Red Rocks Park and Amphitheatre while overlooking the Denver skyline
14. Visit the Colorado State Capitol in Denver
15. Learn how money is made at the Denver Mint
16. Sample some of Denver's best dining, shopping and nightlife at Larimer Square
17. Walk, bike, or horseback ride around Garden of the Gods, a National Natural Landmark
18. Check out the historic Broadmoor Hotel in Colorado Springs
19. Ride the Royal Gorge Route Railroad and see the Royal Gorge Bridge
20. Summit Mount Blue Sky, a 14,265-foot peak, in just a few minutes
21. Ski Vail, one of the largest single-mountain resorts in the country