Have you tried Spotify?
You can create playlists and search for songs or artists, and also has radio channels a la Pandora. I showed my mom, who is 70 and still calls me to ask how to turn the volume up on the TV, and she has a good grasp of it, and has been able to find some pretty rare and foreign artists she likes.
If you're looking for off-line listening, you can pay for spotify premium and it lets you download playlists to a mobile device or tablet (lasts 30 days before you need to connect and refresh), which is awesome for hitting the gym. They also know now have roku app, so I can listen to my playlists through my entertainment system.
My music piracy has gone from 100% to 0% in the past couple of years, and I still don't pay for music.