Beale Street is what there is to do in Memphis. you can look up all the stuff there on the net and make a plan. Personally, it is going to depend on how comfortable you are in big cities at night. Memphis is not considered a "safe" town, but the main drag on Beale Street should be fine at night. take a cab to and from hotel. Going during the day has some places closed but others open. you will have to make a plan what you want to see.
I went to Graceland 20 years ago. it was well worth it then. That was a long time ago. You can learn a lot about Elvis there(20 years ago) and the displays told a lot of stuff about him that wasn't just his music. Elvis was a gospel singer first and formost, he sang about his faith and God's love for a long time before he became the prime time Elvis. Those beliefs were close to his heart, and he was the real deal. he gave away all kinds of stuff, paid for his neighbors homes so they could improve their lives, interacted with the neighbor kids, he was a better human then many and used his fame and fortune in a way most say they will and never do, without bragging, without having to do it in public, he just did it because he thought it was right. At that time 20 years ago, they still were not sure which all homes he had paid for because a lot of them he handed out cash. Most of what they knew was from people coming forward and some spotty records they found in his home.
I can;t say if the tours are the same. 20 years ago was a lot closer to Elvis being around then now, and who knows how commercialized the tour has gotten. but I learned to respect Elvis as a person when I went.
Can't speak to Nashville, even though I was in the Memphis areas for 3 months I was too broke to go up there, I was on a business/trade training trip away from my family.
I will say this about Memphis area:
Do NOT, EVER, go to West Memphis without knowing where you want to go, and DO NOT go at night. (it is the town on the other side of the bridge) I went with a group with a local guy that knew the area during the day to spend 10 bucks on beer and hotdogs and dollar bets at the dog track there for an afternoon, and the local told us in no uncertain terms when it was time to go.
We were also told if you break down you lock the doors(including on the bridge on I40) and you call for help. Parts of downtown Memphis are this way also.
Like I said, take a cab. Better then getting lost in bars on the windows neighborhood. Not trying to scare you but if you are a country folks like me it can be a culture shock. People are good. Not all people, act like people.
Sorry for all the doom/gloom, just be prepared. The trip sounds amazing fun, and is making me think I should plan a trip south to that area again soon.
One thing maybe not on your list is the bass Pro Shop in the GIANT pyramid building. that didn;t exist when I went 20 years ago. It would be on my list nowdays.
