I prefer keeping things relatively simple until moments of tension in the song. Counter Melody and leading the vocals go very far when used sparingly.
My old group had a song where the bass part was actually pretty boring but everytime I would repeat a phrase I would change my selection of notes to bring the feeling of motion.
So initially the bass line like sat around an open A and the 2-4 fret area, then I would move 5th on E, 7th D etc. Basically moving the phrase higher and higher without changing the function of the baseline.
So to the listener, our bass line remains familiar but still feels fresh. Eventually when we hit the high point of the song my last note ended beyond the 12 fret and became the first note of the rhythm guitarists line and the launching point for the lead guitarists' solo.
This creates a huge feeling of motion from the entire band using what was originally a simple, unassuming baseline.