Green Airport doesn't offer a nonstop path to the Balkans, which means every itinerary in business class from Providence to Zagreb routes through a major hub, typically Delta via JFK or Boston into Amsterdam or Paris, or Lufthansa through Boston into Frankfurt or Munich, with Croatia Airlines picking up the final leg into Zagreb. The reality of this routing is that your total journey time often stretches well beyond the ~9.5 hour flying time once you factor connections, so the choice of hub matters as much as the choice of cabin.
Having routed through both Frankfurt and Amsterdam on this itinerary repeatedly, I lean toward Lufthansa's Frankfurt connection when the schedule allows for their newer Allegris-configured 787s or A350s on the transatlantic leg — the suite-style seating with a closing door is a meaningful upgrade over Delta's One Suite, though Delta's product is still excellent and their JFK-AMS routing tends to be more schedule-friendly for Providence departures given PVD's limited early-morning connection windows. Once you're on Croatia Airlines for the Frankfurt-Zagreb or Munich-Zagreb hop, don't expect a lie-flat product — it's a short regional business class, but the ground experience at Zagreb's compact airport more than makes up for it, with immigration and baggage claim rarely taking more than twenty minutes even on busy summer evenings.
My insider tip: build in at least a two-hour connection in Frankfurt or Munich if you're transferring to Croatia Airlines, since their gates are sometimes in a different terminal area requiring a bus transfer, and rushing this connection is the single most common way travelers miss their final leg into Zagreb. Seasonally, January through March and October into November consistently produce the softest business class fares on this corridor, as Croatian tourism demand collapses outside the Adriatic summer season. Given how much these fares fluctuate hub-to-hub, setting up automated fare alerts for this specific routing is the smartest way to catch a premium-cabin deal before it disappears.
