An option that would allow you to select rotation logic for the playlist. Specifically by "Least recently played". in conjunction with the ability to adjust separation rules on a category basis.
Category Selection: Hot Tracks, Top 40, Recurrent, Oldies etc etc
Separation: Heavy Rotation (i.e.: Album Separation 1hr, Artist Separation 1 hr, Title Separation 1 hr, Track separation 1 hr.
Logic: Least Recently Played/Playlist order/Random
This is basically the same principle as most playout software. While a tad more complicated to implement, if this could be done, many broadcasters would drop software/dedicated computer options for this. I know I would ;) MORE CONTROL!