Bellcaptain - - - (my father-in-law is as retired bellcaptain)
Congrats on the house.
While they did build things like the Golden Gate Bridge and the Pyramids without one, a compute might have helped them a bit.
There are several trial programs available like Anyrail and Scarm. You are limited to how many pieces of track you can use without buying the software. (usually about $40)
There are many track plan ideas out there and a software program will save you hours of crawling around on the floor.
Good luck and keep us posted on your progress.