Barranquilla is not very touristy and is not particularly beautiful. There are a few pretty squares and places though. I would suggest staying in the area around the Hilton Garden Inn or Crowne Plaza. There is an upmarket mall with an OK food court as well as a strip of shops and restaurants, some of which were quite pleasant. The immediate area around these two hotels feels quite safe and you can walk around at night. Walk 10 blocks south and it becomes far less pleasant and many locals will advise you not to go to these areas. Most of the rest of Barranquilla seemed quite sketchy to me...