While sightseeing in Denver, be sure to note your elevation: One of the steps in front of the Colorado State Capitol building is marked with a plaque signifying that it is exactly 5,280 feet, or one mile, above sea level. A perfect opportunity to snag a memorable smooch in the Mile High City — “mile-high club” jokes totally optional. More things to do in Denver >>
At 265,000 acres, Rocky Mountain National Park isn't the country's largest national park, nor is it the most-frequented with about 4 million annual visitors (compared to Great Smoky Mountains National Park's more than 11 million visitors). But there is something definitively magical about RMNP, which rises 12,183 feet into the Colorado sky. The main attraction is hiking its 350-some miles of trails that wind through pine and spruce forests, glittering alpine lakes, swaths of wildflowers and if you're lucky, some elk or bighorn sheep. And maybe it's the thinner atmosphere that goes to visitors' heads, but even the most jaded report feelings of awe and wonder after a day or two of breathing in that refreshing mountain air.
In the shadow of Great Sand Dunes National Park and Preserve, the quirky town of Hooper sits atop a natural artesian hot spring, with water flowing year-round into the family-friendly Sand Dunes Pool. On the same property, The Greenhouse is an all-indoor, all-adult oasis with three small soaking tubs and a 10-by-75-foot zero-entry pool. The Greenhouse also has a 10-person sauna, indoor gardens and an onsite bar to help you stay even toastier.
More than 3,000 elk, 800 bighorn sheep and herds of mule deer and moose live in the park. For the best photography lighting and opportunities to spot massive bugling elk, head to Moraine Park just after sunrise. View bighorn sheep at Sheep Lakes May through mid-August and catch a glimpse of RMNP’s ever-elusive moose population along the Colorado River in the Kawuneeche Valley on the park's west side.
In winter you can try cross-country skiing and snowmobile trails and after an energetic day out there is nothing better than a soak in one of the natural thermal springs. You can visit the Buena Vista Heritage Museum or go on a Ghost Town adventure, visit several working art studios and galleries, or quench your thirst at a local brewery. Things to Do in Buena Vista
In winter you can try cross-country skiing and snowmobile trails and after an energetic day out there is nothing better than a soak in one of the natural thermal springs. You can visit the Buena Vista Heritage Museum or go on a Ghost Town adventure, visit several working art studios and galleries, or quench your thirst at a local brewery. Things to Do in Buena Vista 
While it is possible to travel through Rocky Mountain National Park and not catch sight of any wildlife, we venture to say that is an unlikely experience. From everyday sightings of chipmunks and mule deer to the moving experience of viewing elk in rut (the mating season), the animals in the park let you know that you are part of something truly wild. Some of these critters are harder to spot than others - they might camouflage themselves in the trees or hide in the underbrush - but look closely and you may have an encounter unlike any other.
