Coming from the U.S.A. - Looking at a 5-6 day trip in advance of a 14 day Viking Cruise starting in Bergen, Norway next July. Would like to possibly visit Krakow, see the Auschwitz camps, then on to Warsaw then fly to Bergen. Any thoughts/ideas regarding transportation logistics, etc.
Check out the availability and flight itineraries from your home airport to either Krakow or Warsaw. Obviously, it sounds like Krakow would be the best starting point but most flights go through Warsaw anyway because it's the capital and the largest flight market for flights from the US. LOT is the national Polish Airline, but other carriers could work too: FinnAir, Lufthansa, KLM, and even Turkish Air. Everything depends on your home airport.
If you want to see both Krakow and Warsaw, I would try to stretch your trip to at least 6 full days (5 is too short).
If you want to avoid flying, there is the train and ferry option. Take the train to Sweden, from Sweden are ferry connections to Poland.
SAS also has good connections between the USA and Poland. As well as between Scandinavia and Poland.
Note however that if you fly with Turkish Airlines, your flight will not be EU261-protected. (And it will be quite a detour.)