With five major sports teams, an emerging brew pub scene, legal marijuana shops, quick access to beautiful natural scenery, and some of the best skiing in the USA at its doorstep, its no wonder Denver is on a hot streak of eclipsing its annual number of tourists to visit for several years in a row now.
Denver is an excellent launching point for both summer and winter adventures. Rocky Mountain National Park is only an hour and a half to the north, making it drivable for those staying in the city. Some, however, will wish to stay in Estes Park for a few days in order to maximize their time in the mountains.
Extending farther north, the really adventurous use Denver as a launching point for the Mt. Rushmore - Yellowstone - Grand Tetons road trip loop, flying into the city, renting a car, and hitting the road for a week or more, checking off some major sights before returning to Denver for a little rest and a local brew.