I love 8tracks! I can find playlists for every mode and even work appropriate playlists.
It's free! Sometimes the adds get annoying but for the most part it's awesome.
Some playlists are repetitive but I discover new songs and artists daily on 8tracks.

Great app when you are looking for a playlist of a certain genre either for yourself or if you're hosting a party! They have a great selection of playlists, genres of music, and eras. This is such a convenient app if you don't have the time to make your own playlist! It's also free download!