Sorry if already mentioned somewhere…
I think it would be cool if there was a rhythm/timing suggester. Similar to how Suggester recommends chord progressions, this could recommend different ways of laying out the duration each chord plays. So maybe chord 1 is .5 beats, chord 2 is 1.5, chord 3 is 1.5, chord 4 is .5, etc…you get the idea. These could be random timing suggestions or perhaps using a database of rhythms created by artists, or even better a combination of both.