Milwaukee's General Mitchell Field isn't exactly a hub of transatlantic drama, which is precisely why the smartest routing to Luxembourg City requires a bit of strategy rather than luck. There's no nonstop option here, so business class from Milwaukee to Luxembourg realistically funnels through Detroit or Amsterdam via Delta, or through a European gateway like Frankfurt or Munich via Lufthansa, with Luxair picking up the short regional connection into LUX itself. The factual baseline: total journey time runs roughly 8 hours of actual flying, though with connections you should budget 11-14 hours door to door depending on layover length. Delta's transatlantic legs typically operate on A330s or 767s with their lie-flat Delta One suites, while Lufthansa's longer sectors increasingly feature the new Allegris business class on select 787 and A350 routings out of Frankfurt and Munich — worth requesting specifically when booking, since older 747 configurations still fly some Frankfurt rotations.
Having routed through both Frankfurt and Amsterdam repeatedly, I'd steer experienced travelers toward the Munich or Frankfurt connection on Lufthansa when Allegris aircraft are confirmed — the suite's sliding door and dedicated storage make the short Luxair hop afterward feel like an afterthought rather than a burden. Amsterdam via Delta works beautifully if you want lounge access at Schiphol's excellent business facilities before a quick KLM-adjacent or Luxair continuation. My insider tip: Luxair's Luxembourg Findel Airport is refreshingly small and fast — arriving even 60 minutes before a European departure is plenty, freeing up time to enjoy Frankfurt or Amsterdam's lounges rather than rushing.
Seasonally, January through March and again in October-November consistently offer the loosest business class award and revenue pricing on this corridor, as leisure demand toward Luxembourg's finance and EU-adjacent business travelers dips. Because fares and premium inventory here fluctuate quickly given limited capacity, setting up automated fare tracking for this specific Milwaukee-Luxembourg corridor will serve you far better than manual checking.
