If you visit Nashville ,there are two "must sees," in my opinion: The Grand Ole Opry, and this museum. If you're a fan of country music, or just want to learn more about it, this museum fits the bill. I did the basic admission and just toured on my own (there are plenty of placards explaining everything.) Think of it as Ken Burns's series compressed into a few hours. I spent around 3 hours there. I would advise to budget at least 2. There's an add-on to allow you to see the old RCA Studio B, where apparently a lot of hits were cut. I didn't have time for this, but I would think it's worthwhile doing.
Advise to come relatively early (before 10), because it does start to get crowded.