With more time, energy and money, I would model the Putnam Division of the New York Central, known as "the Put."
It no longer exists, but it would be exciting to model it. It ran from the Bronx in NYC up to Brewster, NY. Industries would include dairy farms in Northern Westchester County, and iron/coal mines in Brewster, NY in Putnam County. I also believe there would be transportation of lumber and produce including fruit from orchards and vegetables from farms.
It ran short mixed freight trains, short passenger trains, and sometimes mixed freight and passenger consists.
A great era to model would be from 1945 to 1958 when the Put ran small steam engines (Atlantics) and small diesels (44 ton and maybe smaller).
The trains on the Put would run through beautiful scenery including along the Bronx River and Saw Mill River, and parkways would be under construction by those same river names. Also, there would be a gorgeous Victorian style station at Potantico Hills (near the Rockefeller Estate) and other smaller and simpler stations along the Put, including Yorktown Heights (where I live) and Baldwin Place where there were dairy farms. Lionel's operating milk cars and platform would be perfect on the Put. Also the 97 coal loader in Brewster, and the operating coal dump and log dump cars. Operating fork lift and saw mill would be nice on a model of the Put.
There are books with pictures of the Put that are available, often at train shows in White Plains, NY.
Problem is that I'm quite content with my current eclectic O Gauge layout, tinkering with my trains and scenery and writing things on this on line forum, most of which are silly but a lot of fun.
I would love to have a more serious and skilled modeller than me take on the project of resurrecting the Put so I can visit it, see it and maybe run my small steam and Diesel engines on it.