Probably is a shutdown command line in Mac, I make it a point to avoid using Terminal whenever possible.
Found a couple of workarounds for now: Apimac's "Timer" app will shutdown specific applications by either countdown or at a specific time. (Lots of Mac apps that shutdown the computer or iTunes, not so many that work on any app.)
Also discovered that you can create a time-limited smartlist:
[Media Type]=[Audio] [Rating]=>=4 [Genre]=[Classical],[Classical Pops],[Jazz] ~sort=Random ~t=90m
That one plays a random 90 minutes of classical, classical pops, or jazz music. Can adjust it to whatever music choice or time length you favor. Can also do it as a random number of albums, e.g. three classical albums:
[Media Type]=[Audio] [Genre]=[Classical] [Rating]=>=4 ~sort=Random ~limit=3,1,[album],[album artist (auto)] ~a
This has turned out to be a solution for me both for sleep timing and shuffling by album.
Still would like MC20 to have both features built in, however, for simplicity. I found the smartlist search language mostly by luck while searching Interact.