One of the biggest issues I have with Spotify is when you are offline and search for a downloaded song, nothing will happen after. A suggestion I have is that Spotify automatically plays the next song from whatever playlist the orginial song you requested is in, assuming the entire playlist is downloaded.
TLDR: Offline Radio (But is just the playlist automatically playing after a single ends)
Why do this?
It prevents us users to have to login into our phone again and chose the next song which is annoying.
Sometimes we can forget which playlist a certain song is in, and as a result have no idea what playlist to search for.
I certainly can't be the only one who is annoyed when I am offline and think of a song I want to listen to, and then when that song is over would like to be played similar songs (ie from the same playlist if applicable).