Its often popular to stay near the 'hauptbahnhoff' in Frankfurt - but if you can, try and avoid it. The 1km around the Hbf (hauptbahnhoff) has a reputation for being seedy and full of crime. There are many hotels just five minutes' underground ride away from the Hbf, which will leave you more centrally located for any meals/drink you may want - usually located around Hauptwache or Konstablerwache.