The largest in the world is King Khalid airport in Saudi Arabia, followed closely by Jeddah (that's by land area). The largest one in US is Denver International, it has 6 runways and looks like a big swastika from above. Atlanta is the busiest one.
Money does not bring you happiness. But it's better to cry in your own private limo than on a cold bus stop.
Currently the biggest major airport, as far as amount of runways go, is Dallas/Ft. Worth (DFW) with 7. Chicago O'Hare shut down 18/36 and thus has 6. Plans have been drawn for up to 11 runways at Denver, although that will never happen.