I've been messing around with the free version of Spotify. I like it better than Pandora. Better mix, and newer music. What does the Premium version add?

I'm also wondering how I can set up an interface with this app and my AVR. I really do not like using my phone. I want something that will just sit there on my equipment rack and be available for use, so I do not need to have the 65" TV turned on. Some type of interface I can stream music, and also find my music collection on a hard drive. I was looking at one of the Chromebooks, but I'm not sure if they have a very good audio output that I can plug into the receiver?? Another thought was to get one of those 15" touch screens you find at retail stores, but then I'd need something to run the app.... I'm overthinking this. What should I do??