There's no elegant way to get from the Lowcountry to western Poland, and after routing through this corridor a dozen times, I've made peace with the fact that patience is the real currency here. Booking business class from Charleston to Poznan requires a connection—there is no nonstop option, and there never will be given the market size—so the real decision isn't which airline flies the route, but which hub you're willing to build your itinerary around. Delta's transatlantic metal via JFK or Amsterdam pairs well with Delta One suites on the long-haul leg, while United typically routes through Newark or Chicago into Warsaw or Frankfurt before a short LOT Polish Airlines hop into Poznan. LOT itself operates Boeing 787 Dreamliners on select long-haul segments with a proper lie-flat business cabin, and using their Warsaw hub as your final connection point is often the smoothest way to close out the journey, since Warsaw Chopin's transfer process for Star Alliance partners is efficient even during peak summer congestion.
My preferred sequence, after years of trial and error, is routing through Amsterdam or Frankfurt rather than a UK gateway—Heathrow's connection times can be brutal for a short final hop into Poland, whereas Schiphol and Frankfurt tend to have shorter walks and better lounge access for the last leg. If you're connecting through Warsaw on LOT, arrive with enough buffer to enjoy their business lounge rather than sprinting; the Poznan sector is served by regional aircraft, and those gates can be a hike from the international arrivals area. One insider trick: award availability into POZ often opens up on LOT's own inventory before it shows on partner searches, so checking LOT's site directly—even if you intend to book through Delta or United miles—can reveal seats invisible elsewhere.
January through March and again in October and November are your best windows for value, as this is when European corporate travel dips and premium cabins get discounted to fill seats. Given how fragmented and seasonal pricing is on this city pair, setting up fare alerts for the Charleston–Poznan corridor is genuinely the smartest move you can make before committing to a itinerary.