> Seeing the real Apollo 10 (I don't remember which module) sticks very clearly in my memory.

The only part that made it back to Earth was the Command Module, so if you saw something from the actual Apollo 10 mission, it was the CM.

I have taken my kids to them at various ages (from five upwards). I think lots for both adults and children.

The National Gallery used to do great guided tours for kids, explaining paintings in a fun way.