I have stayed in many of Frankfurt's city centre hotels (I work for a German company) including the Arabella. Rooms are nice and big, however mine had this whole "black lacquer furniture" thing going on that reminded me of a 70s porn set. I also like the Hilton, good location, good size rooms and they have a patio outside where you can eat breakfast. If you want to be close to city centre then avoid the Radisson SAS - it is a cab ride away. Whilst the look and feel is very modern, the rooms are tiny - you really could not swing a cat in them.

Despite being a regular, I cannot comment on bars and restaurants as my visits are no more than: airport --> office --> hotel --> office --> airport