The biggest was probably the Atlanta International Airport. The place is spread out more than any other airport I've been to.
East Midlands, best aiorport I've been to.
Second goes to Manchester, third RIX, 5th LPL, 6th CRL, 7th Stansted
Palm Beach International Airport, Florida
Heathrow Airport is the best one....
Luton airport is the best airport I've ever seen. There are restaurants, shops, bars and even a currency exchange in the arrival lounge. It has parking spots also.