I would like to be able to mix together and shuffle a couple of playlists together on the fly. I can see that as being possible if I could start one playlist and then add another to the queue which already contains the first playlist. Alternatively, create the ability add entire playlists to a new playlist in order to accomplish the same thing. I am mainly mainly intending this idea be implemented for mobile.
As mentioned, you could just used Playlist folders or add all songs of a playlist to another one.
If you want a way to queue an entire playlist, please add your kudos and comments to this idea: