I support Jeff's points. Follow your joy, but don't give up on bass. Though playing songs on guitar is more melodic, bass is the subliminal powerhouse of band music. I have always maintained that melody, chords structure, lyrics, harmony, and even stage theatrics are just there to distract your mind while the bass and drums do the heavy lifting. It has always seemed that if you can get the audience to start moving their ass, you have won. Bass and drums are where most of that win comes from. It is kind of magical, since most people don't even realize that you have slipped right past their concious mind in doing so. They just start shaking and once that happens you have an appreciative audience.