Nuremberg's tidy little airport doesn't accommodate widebody jets from Tennessee, so anyone booking business class from Nashville to Nuremberg is really booking a strategic connection—and the routing you choose matters more on this itinerary than almost any other transatlantic pairing I track. There is no nonstop option, full stop: Delta, American, and United all require a change of planes, typically through Atlanta or JFK before a European gateway, then a short regional hop into NUE. The most seamless version I've found over dozens of bookings is Delta via Amsterdam or Paris, connecting onto an Air France or KLM regional jet, since Delta's transatlantic metal on the BNA–ATL–AMS routing puts you in a Delta One suite with a closing door on the long leg, which is where the real rest happens.
American routes typically funnel through Charlotte or Philadelphia into London Heathrow or Frankfurt, and their Flagship Suite on the 777 or A321neo transcon-style seats (depending on aircraft assigned to the Philadelphia leg) is worth requesting specifically—ask for the 777-300ER when booking, as American occasionally swaps in older 767 business cabins on thinner European feeder routes. United's preferred path runs through Newark or Washington Dulles into Munich or Frankfurt, where United Polaris seats offer excellent bedding and a proper pre-departure lounge experience at Dulles's Polaris lounge, arguably the best pre-flight meal in your entire itinerary. My insider tip: build in a two-hour minimum connection in Frankfurt or Munich rather than Amsterdam if your ticket allows an open-jaw choice, since German rail and regional carrier reliability into Nuremberg is notably stronger than the Dutch short-hop network, which suffers more frequent delays in winter fog season.
January through March and again in October and November consistently produce the softest business class fares on this corridor, largely because Nuremberg's trade-show calendar (Christkindlesmarkt excepted) creates lighter leisure demand outside summer. Given how volatile award and revenue fares swing across three connecting carriers and multiple European gateways, setting up fare alerts for this specific routing will save you from overpaying on a journey that already asks for patience.
