I don't know about Poland, but we've rented cars in France, Italy, and Hungary using just our valid US license - no issues. Maybe find a deal you'd want at a rental shop and email them directly to confirm?
Aha! Not sure why I didn't think just to check directly with a rental company in the first place.
I just checked Avis's website (the Polish one, with Location-specific Terms & Conditions)
Driver's License Requirements
International Driving Permit is required unless driver has a license issued within the European Union.
US, Canadian, Australian & New Zealand licenses are accepted (International driving permit not required for renters with a US, Canadian, Australian or New Zealand license).
Applicable to all drivers, a valid driver's license must have been held for a minimum of one year.
Exception: A driver's license from Greece is acceptable.
An International Driving Permit (IDP) serves only as a translation of a driver's existing license, and by itself is not acceptable for vehicle rental.
Good enough for me! Apparently there are other wedding guests arriving into the same airport around the same time, so I don't think I'll need to do any driving at all, now! It's nice to know that it's an option without the IDP though. As it's an airport, I imagine I imagine I could also go from counter to counter until I find a company there (first-that can understand me, as I speak NO polish) and will accept my US DL.
Thanks for that, mozingod, must have had a brain fart (or took the US Embassy's instruction as the be-all and end-all).