I knew one really good guitar player whose instructions to new bass players in his band was "Nothing above the 5th fret." I understand that attitude, but Leland Sklar plays above the 5th fret a lot, and still makes it very musical.
My favorite thing on bass is playing inversions, as James Jamerson did on some of his Motown recordings. Listen to his playing on Marvin Gaye's "Pride And Joy", a KILLER "walking" bass part!