Scott,

Try Steinberg's Groove Agent 3. Pros include: 25 variations per 'style', 25 fills per 'style', auto fill function, 1/2 time function, tweakable 'humanize function' (quantization), variations can be selected via midi keyboard, built-in percussionist module which will play in sync with the main drum module etc...

Cons include: Only built-in 'styles' (I think), not a lot of styles in each genre, cost etc...

I am sure at some stage in the future Groove Agent (or similar) will become the heart of my arranger system.

Kind regards,
Mark