There's definitely quality non-profit radio stations (NPR affiliates, for example) depending on where you live. At worst you get the fund drives that are annoying (but understandable) for a week.
I listen mostly to NPR. Occasionally (pledge drives, reruns, shows I don't care for) I will turn to traditional radio to fill the void while driving (older car with no MP3 interface). It's amazing to me how many commercials they have! They feel interminable and it feels like at least half the channels have commercials playing at any given time. It really makes me appreciate KQED (local NPR station) and is the reason I support them.
Fortunately, I'm seeing more and more cars support USB interfaces. Now I can just load up a USB stick (they are so cheap) with my music and old episodes of This American Life and I'm good to go for hundreds of miles.
I've been listening to a commercial rock station on HD (KSAN fm on HD2), and it doesn't have any ads or announcements. There are silly "you're listening to station X and it's awesome" announcements every now and then, but that's about it. Everything else is just music.
I have no idea why they don't have any talking or ads, but i don't mind. I suspect it's because this is an offshoot station--there is the normal station, with more mainstream classic rock, talking and ads and then there is this "HD2" station with no ads and different music.
I really don't know why they run this station or even how it makes any money, but it's there and it's nice. So, for whatever reason, not all commercial stations have ads.
I listen to NPR occasionally, but I'm also not one of those people that wants my media chosen randomly. I usually consume NPR-type content in podcast form. (Although more and more podcasts are becoming advertising-driven... grrr.)
There's definitely quality non-profit radio stations (NPR affiliates, for example) depending on where you live. At worst you get the fund drives that are annoying (but understandable) for a week.
EDIT: This assumes you're in the U.S., though.