I've always enjoyed Grooveshark.com, which was suggested by a colleague about 8 years ago.
As far as I can tell, it is essentially like Spotify, but a little bit more flexible when it comes to playlists. Also, apparently a great venue for virus-catching.
Regardless, Spotify is fairly straightforward, andI love that it offers a bio of the artist/group, and also provides tour info. It would, I think, be useful should we decide to reinstate Friday Morning Music.
In days past, staff members would volunteer to select about a half-hour's worth of music to play over the library speakers between 8:30 - when most staff arrive - and 9:00 - when the doors the the library vestibule open. We used either burn a disc or swap cds on the library's handy-dandy boombox, but it would be soooo much easier to have a playlist on a phone or tablet.
I made a (super-short) play list of work-appropriate songs that could be used for this purpose...