Build a diorama to work on scenery skills, then start a layout based on the Ulster and Delaware/NYC Catskill mountain branch. Already have much of the equipment. Alco locomotives, mostly appropriate freight and passenger equipment, work and MOW equipment. Track planning will be a killer. Small cities on both ends. A riverfront yard in Kingston with a nearly 4% climb through a tunnel to the NYC and O&W interchanges. Two three percent mountain grades, lots of very small towns. Twisting and turning route. Moderate agricultural traffic, including farm supplies and milk. Note to self, get N scale Architect's Sheffield Farms creamery, and Hanford Mills kits. Good luck to everyone else on their projects.
Frank