I've never heard of anyone comparing to a football field in the Area domain. Of course this is cultural, but at least in the US - the length is what is commonly compared.
Definitely country-specific, I'd expect it to be used to describe areas (and football stadiums be used to describe "number of people"). But footy fields in Australia are typically oval shaped!
"Olympic swimming pools" can be used for length, area or volume (but "Sydney Harbours" are only used for volume).
PS just tried the tool and couldn't find any of the above "units", not even "football fields".
