Memphis is a great time, you must hit Beale St. Take the tour of Gibson Guitar and Sun Studio. Also Memphis is quite dangerous more than a block or so from Beale. Free bus from Beale to Sun, do not walk. You can pick up the bus just across the street from Gibson. I start on Beale around 11AM and head back, ah, late.
Graceland can also be reached by the same bus or take the Spyder, safe parking. An hour and a half south on highway 61 is the Delta Blues Museum in Clarksdale MS. Well worth the trip and across the street is the Ground Zero Blues Club. As in highway 49 & 61 is ground zero for the blues. Have you ever heard of the Crossroads? That's 49 & 61 where Robert Johnson sold his soul to the devil for guitar greatness. Or so they say. Head a bit further south or due east then pick up the Natchez Trace to Nashville. All of the Trace is nice if you have the time.
Staying near on or Beale is very expensive. I use the airport Best Western then take a cab back and forth. They have a fenced in parking lot. The desk will hook you up. Then just phone the driver when you're ready to leave.
Around 15 years ago I rode back to the motel from Graceland after dark. The junkies were out driving around. Stop signs and traffic lights were suggestions. Never again. Now I hire a ride.
Oh yeah, you need more time.