Another vote for the Flying Saucer...
And if you wind up on Beale street, go towards the east end and find the New Daisy Theatre, in front of which you will most likely find one of favorite musicians set up on the sidewalk giving a free show, his name is Richard Johnson
and he's an incredible one-man-band hill-country blues artist. Even if you don't like blues music, it's just incredible to watch him play.
And if you get really drunk and want to experience some craziness, head a few blocks off Beale to Raiford's Hollywood Disco
... Just be forewarned, the only thing they sell in there are 40's of Bud Light, so when they ask if you want a beer, that's what you'll be getting. And don't be frightened by the door-man that's packing heat. It's been about 6 years since I lived in Memphis though, so that place may be totally unsafe now, it was only marginally safe 6 years ago, and I was just out of college and didn't give a crap.