I thought those runways at LaGuardia were a bit short... Our runways at Denver International Airport are 12,000 feet long (and 4,000 feet apart), and there is a sixth, 16,000-footer, in the works, which will allow a fully-loaded jumbo jet to take off during hot weather. This sixth runway was supposed to be built along with the rest of the airport, but was omitted due to - you guessed it - cost overruns. DIA can now seek federal funding for this runway, which, it is hoped, will attract more international flights to Denver.
BTW, there is enough room at DIA for 12 runways. We're talking about a total area of 53 square miles - almost twice the size of Manhattan Island.
I flew from Denver to LGA on a 767 once or twice.