The SimplySpotify App allows users to manage their spotify playlists locally. SimplySpotify lets you combine and shuffle multiple playlists at once, even from mulitple users' private playlists.
Just sign in to spotify on the first screen, chose your playlists you wish to import and then let SimplySpotify work with your songs. Once songs are imported they can be shuffled locally, allowing
multiple different playlists to be shuffled together at once.
Interested?
Search for SimplySpotify on the GooglePlay Store to download!