Which is Best for Promotion? Blog Talk Radio,Commercial Radio, or Public Radio?

The intrepid Dani Greer's enlightening interview about blog book tours, which was hosted by Chris Hamilton at Blog Talk Radio on Sunday, made me think. If you can't pay for a radio commercial, which is the best way to plug a book? Is it better to be a guest on an Internet talk show, such as Blog Talk Radio, or a guest on a commercial or public radio talk show?

On the one hand, the Internet spreads its tentacles further and further every moment, reaching more and more people. Its surfers are constantly venturing into new areas of exploration. Many of them land, stop and listen to podcasts, blog radio shows and the like. Since blog radio shows are relatively in their infancy, a guest on one can often claim a huge chunk of time, such as Dani's hour last Sunday.

On the other hand, commercial radio has been around a long time. Its listeners are loyal. If an author were a guest or a caller on a favorite program, followers might be swayed to buy that author's book. The catch is it's not that easy to get your say on one of these programs, especially for more than a few minutes.

I would be remiss if I didn't mention public radio talk shows, such as Michael Feldman's Whad'Ya Know?, on Saturdays. Authors on such shows receive individual attention and opportunites to promote their books. Listeners to public radio are also loyal, but their numbers are not as great as on commercial radio.

So, given the choice, which would you rather do? Why? Have you already been a guest on any or all of these type stations? How did you like it? What were the results? Please share.