I really enjoyed the Durango to Silverton Train..
4 corners was a sight to not see again. Monument Valley and Canyon DeChelley where much better, even if in Arizona.
Royal Gorge bridge is interesting. I recall it being over 1,000' above the river, and you can take a incline rail car to the river, to look up at it, walk across the bridge, or just look around from the top side. You can also ride a excursion train up and down the canyon at the bottom of the bridge, some of it's bridges are hanging above the river, because the canyon is so narrow there was not 8' of space on either side of the river to place the rails.
Pikes Peak is the highest now paved roadway in the United States. It reaches 14,141 feet altitude, and you can drive your car all the way to the top. Make sure that you are out of overdrive, or in '2' gear on the way down, as the brakes might overheat if you are not taking the grade in the correct gear when going down the mountain. Signs warn of the problem of overheating your brakes, still there is a safety checkpoint 1/2 way down the mountain, where they use infra red thermometer to check for overheating brakes, and send you to the nearby visitor's center for a mandatory 30 minute break if your brakes are to hot.
So many other places, how to count them? Remember that at 5,000' altitude, it is a bit more difficult to breath. So climbing a mountain will be much more difficult than in your home state. It is recommended to spend at least 2 days not doing anything strenous, until you have been at 5000 + feet altitude for about 24 - 48 hours. You have to breath about 25% more to make up for the lack of oxygen in the air. And it is REALLY easy to get a sunburn on even a partly cloudy day, the higher altitude means less air to bock out the sunlight.
Fred.