There's space to park up but don't expect to be able to pick who leaves first...I'd be amazed if there wasn't space for all the aircraft to be put down - most airports don't run at 100% capacity, and if needed you could park them closer together than normal/park them in areas that wouldn't normally be used for parking (IE by the terminals), or even where the airport has multiple runways, on one of them as a last resort.
Halifax, Nova Scotia on 9/11 - http://www.airliners.net/photo/0188171/M/