Eastern Slovakia is not a place most premium travelers stumble into by accident, which is precisely why the routing deserves careful thought. There is no nonstop option, so business class from San Diego to Kosice always means building an itinerary through a major European or transatlantic hub, and the connection you choose shapes the entire experience. Delta offers a natural gateway via Atlanta or JFK into a European partner hub, while Lufthansa's Munich or Frankfurt connections and Turkish Airlines' Istanbul hub both feed into Kosice with reasonable frequency. Total journey time hovers around 13 hours of flying, though with a connection you should realistically budget 15-18 hours door to door.
Of the three carriers, Lufthansa's long-haul product deserves particular attention if your itinerary includes their newer Allegris cabin, which features suites with closing doors on select aircraft — though on this specific pairing you're more likely to encounter their proven long-haul business seat on A340 or 777 equipment, still a fully flat, direct-aisle-access product. Turkish Airlines routes everyone through Istanbul's IST, and I've found their business class lounge there — sprawling, with a putting green and live cooking stations — is reason enough to prefer that connection if you have a few hours to spare; my insider tip is to request an Istanbul layover of at least three hours specifically to use the lounge's à la carte dining rather than grabbing food at SAN or in Munich. Delta's Delta One suites on transatlantic widebodies offer the most consistent domestic-to-international continuity if you're loyalty-minded and already hold SkyMiles status.
Seasonally, January through March and October into November reliably produce the softest business class fares on this corridor, since Slovak business travel and American leisure demand both dip outside summer and the December holidays. Given how thinly this route is served in premium cabins, availability can swing unpredictably even in low season — so rather than checking fares sporadically, set up automated price tracking for San Diego to Kosice business class and let alerts do the waiting for you.
