The National Naval Aviation Museum is on Naval Air Station Pensacola, about 25-30 minutes east of Perdido Key. It is one of the most genuinely impressive free attractions on the Gulf Coast — over 150 restored aircraft on the floor, a Blue Angels exhibit (NAS Pensacola is their home base), simulators, an IMAX theater, and the WWII memorial garden.
Critical: the museum is on an active military base. Access requires going through the NAS Pensacola gate. Civilians can enter for the museum but you need a current government-issued ID, and access policies sometimes change for security reasons. Check the museum website for current entry rules before driving over.
Admission to the museum itself: free. IMAX and simulators are extra. Plan 2-4 hours minimum. The cafeteria on-site is fine.
This is one of the answers to “what do we do with the kids on a rainy day on the Key” that’s worth the half-day commitment. Older kids who care about planes will lose their minds. Younger kids who don’t care about planes are still impressed by the scale.
The base also houses the Pensacola Lighthouse (climbable, separate small fee, great view), which makes a half-day stop into a full-day plan.