Bill makes a good point about making your arranger sound less repetitive by playing "live" bass.

Arranger bass lines can be very unmusical especially in swinging walking bass lines and certain Latin styles. The problem is the arranger doesn't what chord you're going to play until you play it. A good bass player will connect the chords with passing tones that lead smoothly to the next chord.

Confession.... I almost always play auto accompaniment bass, but someday I hope to do more LH bass.

I personally have found longer 16, 32, bar styles with fills can present problems because sometimes I end up getting fills played when I don't want them. This particularly happens when playing songs that have odd phrasing or for whatever reason you need to add a few bars at the end of the phrase.