It would be nice to have the ability of add a complete playlist to the current play queue. Also, I'd like to be able to randomly reproduce the songs added to the queue since currently they need to be reproduced immediately after they were added to the queue. For example, I have two playlists, I start playing the first one and then go to the second and add it to the queue. This way I would be playing two playlists at the same time which would be awesome!
We just wanted to update this to say it's possible to add all tracks from a playlist to your queue on Desktop. To do so, just head to your playlist > select all tracks using 'Ctrl/Cmd + A' > right click and select 'Add to Queue'.
There aren't currently plans to implement this on Mobile, but if anything changes we'll update you here.