Why model in S? It’s the perfect size of course. Falling between the larger O and smaller HO, S offers all the advantages of O (smooth, reliable, running; plenty of room under the shell for motors, decoders and speakers; easy to handle; easy on the eyes; great detail and sound quality) while reducing the needed space and minimum track radius to something most modelers can accommodate.
S is a great scale to build in. As a common architectural scale a wide variety building materials, components and parts are available at 1:64. In S 1″ = 1/64″, 2″ = 1/32″, 4″ = 1/16″, etc. all commonly available sizes in wood and styrene. 1″ = 0.016 of an inch wire, 3/4″ = 0.012, 1 1/4″ = 0.020, etc. All common wire sizes found in most hobby shops. No annoying decimals or fractions or approximate representations of a given measurement as found in other scales. S makes modeling easier and that means more detail you can actually see.