Taking our kids (both US citizens) to Switzerland, Germany and Italy for spring break. Their passports expire 3 months and 13 days after we return. The State Department website in some places says 6 months validity after return date is required, and in some places it says 3 months (sometimes on the same page e.g. the Switzerland Country Information Page). We are flying United and Lufthansa. United told us 3 months was fine. Lufthansa declined to answer and said check with the governments. Swiss government websites seem to indicate 3 months, but then there's the US DoS which has me uncertain, as well as several forum posts that indicate it's most likely an airline employee who would make an issue of it.
Benefits to waiting to renew: If they can travel on their current ones, we save application and expedite fees in the short-term (so more for the trip), and we can renew after my daughter turns 16 when she can get a 10 year passport.
Drawbacks to waiting to renew: My anxiety, lol. I would only wait if we can be confident we won't have any issues. Is anyone able to offer any confirmation on the validity requirements and likelihood we might face issues? And if you encounter a mis-informed airline employee, what are the odds of successfully convincing them your documents are fine?