New York Central
Modeling NYC provides the chance to have both smoothside- and stainless steel lightweight cars as well as the traditional heavyweights. Diesel locomotives include the E7 and E8 from GM as well as ALCO's PA. The best looking choice for a steam locomotive is Con-Cor's J3 Hudson, something that just totally captures the essence of the late 30's and Art Deco design.
Shortly after I started model railroading I bought Kato's four-car and six-car smoothside sets. Although these are really Union Pacific cars simply painted for NYC, they look rather good. I think the colors are probably a bit dark, but it's not like I have much choice!
Con-Cor makes great Budd cars in N scale. Unfortunately, the font on the NYC ones does not match any picture I've seen. The lettering is in a serif font when all the cars seemed to have had a sans serif one. Microscale makes two sets of decals for "NYC Silver Passenger Cars." Decals for the heavyweight cars are out of print at the moment, though I think I have a couple sets from when I mistakenly ordered the wrong ones.
On a passenger-focused layout, I could see two or maybe three NYC trains. One would be the J3-lead Twentieth Century Limited. Another would something like the Empire State Express in stainless. When fully finished, each train would ideally have American Limited Models working diaphragms, DCC-controlled interior lighting, Fox Valley semi-scale wheel sets, body mounted Micro-Trains Lines couplers (Z scale on the front of locomotives and the rear of the observation car. Gold Medal Models makes an etched brass detail set for the Kato cars that has value for others as well.