I think Google play music has come along way.  I have the family subscription so my whole clan can have their own "bucket". 
I play the radio stations a lot... When I like a song I add it to my play list called "Keep" which I have set to keep as downloaded on phone.  
The only EVIL PART is I used to Just stream Songza at work for free on a Sonos  system. It is in a place with lots of people so didn't want to use my personal acct.   Now after Google  bought Songza they force you to have a paid subscription on GPM to use the mixes.  Boo!