Travel
We would recommend booking your stay early, just to guarantee a spot for a reasonable price.
Another option for stay is doing a VRBO or Airbnb.
Out of Towners:
We would recommend renting a car, so you have freedom to explore the park.
OR
There is a shuttle service from DIA to Estes Park http://www.estesparkshuttle.com/DIA-airport-shuttle
Estes Transit is a FREE shuttle system the town provides and there is a taxi service in the area
Denver to Estes Park is around 1hr 30 mins (65.8 miles)
DIA to Estes Park is around 1hr 30 mins (58 miles)
Kalispell, MT to Estes Park 15hr 12 mins (970 miles)
Mankato, MN to Estes Park 12 hr 30mins (780 miles)