Another option is to book a flight with United miles which allows free flight changes as long as the departure and arrival cities remain the same. I would consider about 2-3 weeks out from departure, trying to switch to MCI-CLT-MUC-DUB. Lufthansa has non-stop daily flights from Charlotte to Munich (A330) and I've heard their first class is superior. I've only flown economy on that route multiple times and even their economy is great. You could also probably pick up ORD-FRA-DUB all via Lufthansa. Lufthansa usually only offers their 1st class cabin 2-3 weeks in advance so you would need another first class *A flight booked in order to change to this if it opens. Flying through Germany probably adds $40 in taxes per ticket.