Staying with Root/5 bass lines (or any bass line): It is critical to the groove that you decide the duration of each note and how it will sound. If sounding on beats one and three, either sustain each note in to the next beat or be certain that the space between notes is exactly the same duration as the notes being sounded! Otherwise, even though your articulations are dead on, inaccurate spacing will sound as though you are rushing and dragging thus the groove will be destroyed! Also, for straight ahead jazz swing, sustain like crazy! For western swing, experiment with shorter and shorter quarter notes. If the drummer is playing '4 on the floor' (quarter notes on the bass drum), creating shorter quarter notes on the bass will totally change the groove and can be interesting even in a jazz setting. On the other hand, if the drummer continues to play all 4 beats on the bass drum during a jazz gig, throw his bass drum pedal out the window on your first break! Remember, in jazz the bass marries the ride cymbal. For all other grooves think bass drum and hi hat.