I am still surprised that the Fowler Dream Layout doesn't get mentioned or noticed. It is located in Florida.
This layout is 48' x 84', is detailed in realistic O scale, has running rivers, a passenger station that is wonderful and on and on.
But, the coolest part is that that it is a modular layout that is built of steel frame modules that all fold for transport and roll on wheels.
Take the time to view the galleries of photos. You'll like it.