I recently started using an iPhone and I noticed that there is no way to view the play queue on an iPhone. Also, to queue a song on any device you must right click (or click more on mobile) and then click queue.
So my two ideas/suggestions are 1. Add the "Play Queue" feature to iPhone. And 2. Add a 1-click/1-touch way to queue a song.
This would make it much simpler when you are playing music the car or when working out and you want to spend the least amount of time messing with setting songs in the correct order.