I like the unusual outline of the Jones and Laughlin tank car offered by Sunset (and others in the past), but I suspect that they seldom traveled very far from the J&L works near Pittsburg, so would be out of place on the Rio Grande in Utah (for example). I'll run one if I want to (it's my RR, after all) -- but was just wondering if anyone knows about how they were used.
Another unusual car is the helium tank car that Pecos River brought in (with stacked cylinders for helium gas). West Texas was the only source for helium when the Navy started using it for their dirigibles (and the U.S. refused to sell helium to the Nazi-controlled Zeppelin company, which is why the Hindenburg was filled with hydrogen when it exploded in New Jersey). I doubt that these helium cars traveled around the country -- they would have gone straight from Texas to the Navy's dirigible bases on the west and east coasts. Does anyone know more about how they were routed?