Revell released a B-17F (raised panel lines, minimal interior detail), Monogram released a B-17G (raised panel lines, better interior details, with & w/o Cheyanne (sp) tail turret)
Monograms other WW II 1/48 bombers include : B-24 (D & J), B-25J, B-26B&C, B-29. German bombers include Ju 52 (Spanish Civil War bomber), Ju 88A, Heinkel HE 111(2 versions) Hobbycraft also made some Luftwaffe bombers.
Accurate Miniatures makes a BEAUTIFUL B-25 (different versions-designations escape me at the moment)
Tamiya produces a Mitsubishi G4M "Betty," and an Avro Lancaster.
Some 1/48 Luftwaffe bombers released by DML/Dragon have been re-released by Monogram (Pro Modeler)
There are also many vacforms available.
That's all I can think of at the moment. If I missed any, others will be able to round out the choices.
Hope this helps !