I did the Real Madrid tour/museum about a decade ago and it seemed, from memory, heavily reliant on technology and story telling rather than physical memorabilia. That said, the passage of time may have clouded my memory.
I did the Barça tour about 25 years ago, and my main memory is that one of their ex-players was the spit of Robbie Williams.
I bet he was a better singer. I'll only get 1/50, mind.