Nick - the only thing I can remember about cabin seats is that the a/c was certified to carry (I think) 125 passengers. But with JFK departures often load-limited as they were, I think 100 was a sensible decision. Some clever arrangements meant it looked bigger and airier than it was. Most passenger feedback seemed to indicate the cabin layout was good enough - not First Class, but then you only had to sit there for 3.5 hours...