I would like an option to go back to the playlist where I last selected the current playlist. For example, if I select an artist's album, I'd like to press a key (up perhaps, through configuration?) to go back to the list of the artists' albums. This works the same as now, whereas if I am on one of the artist's albums, and don't selected a playlist, and I hit up, I go back up to the next-highest playlist, all of the artists' albums again.

Call this function "Previous playlist" to map a button to that configuration perhaps.

Me too!
It bugs me that only during playlist selection is up 'up', but during play it 'stop' and I can't go back up the playlist. Makes me start from the top again to go to next album of an artist.