Tex, I've only been to a few. The Smith' and Wright-Patt are both awesome. The Deutscher Museum in Munich (Germany) has a great aviation department, too.
Arcey, you mentioned the Junkers JU-52 tri-motor, or as it was often referred to: Tante Ju (The "J" is pronounced like a "Y") - Which translates to "Aunt Ju" (pronounced You.) During one of my many trips to the main airport in Frankfort, (Rhein Main Flughafen) Germany I heard a different engine sound and looked up to see a beautiful white JU-52 with a red cross on its tail coming in over my head. The red cross on white is the fleet colors for SwissAir, and they were having some kind of Anniversary in Germany. It was cool to see the old bird coming in ... and then I spied another one further back in the pattern! I was doubly excited!
*
*
*
*
*
*
Until I saw a third JU-52! All were painted the same and they were coming in one after another after another! It was awesome! I've seen a couple more flying since then, but to see three in a row, just doesn't happen to everyone every day!!!