Denver Airport has three terminals – A, B and C
Terminal A hosts Frontier’s regional fleet, operated by Lynx, and is the best terminal for spotting. Inside, walk to the end of the terminal where there are large glass windows. This overlooks the commuter aircraft, and across to the United gates. This is the best spot for covering most movements, although the airport is so big and has so many runways that it is impossible to cover everything.
Terminals B and C also both have large windows at their gates, which offer views of aircraft moving around.
There are few accessible views from around the perimeter due to a lack of public roads.
Anyone know of any other good spots? Please comment.