This post has bought up a few interesting thoughts for me;
First of all from the heading I thought you were going to request a playlist playcounter which I think would be useful - to see how often a playlist had been used.

Tracking how many times a song has been played in each playlist would be interesting as well as having the ability to select a song to see which playlists it is part of.

I also use the played# to sort by, however for me if a song appears in multiple playlists I still want the least frequently heard to appear first even if it appeared in a previous playlist. Ultimately the more flexible MM is for this type of thing the more useful & the wider its appeal.

Using Auto-Playlists to sort by Played# and then Random is a great way to keep them fresh. A problem occurs however when a particular genre is used in more than one playlist. The play counter being universal will place tracks played in a different playlist at the bottom of the order all playlists.

For example, a "Lunch' playlist may have the genres 'Reggae', 'Pop' and 'Rock'. Then the 'Dinner' playlist will have 'Hard Rock', 'Funk' and 'Rock'. The problem being that because both playlists include 'Rock' this genre will get played out before the other genres.

A solution would be to create a play counter for each playlist. I'm not a programmer but I was thinking if MM could simply create a custom field for each playlist, this field could be used to track the # of times a song is played by that playlist. Then the playlist could sort by that field instead of the generic PlayCount. Whatcha think?