Interestingly Radio Helsinki is a radio station that doesn't have playlists. Therefore they play every day 99,5% different songs than yesterday. I listen to that station when commuting and I tend to end up finding 1-2 new artists or albums on daily basis. At least for me Spotify manages just to suggest annoying and mediocre crap, if I try their random radio or what ever it is called. That's the difference between qualified and experienced DJ and some algorithm randomizing songs.
Now, it was a small station, but I had thousands of listeners in the country who tuned in online (was broadcast on DAB+, AM and online) and the main reason they gave was because of the bands I played that never got airtime anywhere else.
It also made me happy that other people got to hear my favourite local post-rock bands, and really helped with getting interviews ;) Was a lot of fun. I miss it to be honest, and am sad that it's going the way of the floppy disk...
One show I did find interesting was "Metal Roots" -- it was on Saturday sometime in the afternoon -- usually when I wasn't driving. The shows I did catch were quite amazing -- places like indonesia and south america. Learning something new.
I've seen the same w/ Radio Helsinki (lived there for about 1/2 a year in a previous life), CBC Radio 3 Sessions, etc. But most of the US doesn't seek out anything more than the local cumulus station.