I'm glad someone came up with a warning about the crime rate. We left Memphis 20 years ago, and were thankful to get out alive.
That said, there's not a lot to see other than Graceland. I think the Pink Palace Museum is still open, Brooks Museum of Art, Peabody Hotel ducks (they march from the elevator to the fountain in the AM and back in the PM). The Rendevous is famous for it's barbeque ribs, and is a half block down the alley in front of the Peabody. Beale Street is OK if you like bars and blues, but be sure to leave by 11 or 11:30. Things get rough after that.
In February the weather is cold and dreary. It will feel warm to you, but 40 to 60 for high and teens to 50 is cold next to the river. If you get any snow or ice stay at your hotel. Memphians have no clue how to handle bad weather and the city becomes a giant parking lot! The trees will still be bare, so you won't see the city at her best. Spring in March/April is beautiful with the dogwoods and azaleas and tulips.
As you can see, I have a love/hate relationship with the city. We lived there for 23 years and my kids grew up there, but I was happy to say goodbye and have been back twice since 1992. That was 2 times too many.