Opening and closing with a song is definitely a good way to go, I vote you keep that trend up. Aside from that I think the talking portions are much more fun than the music, so whatever you do it should tend to lean towards a majority of time spent talking as opposed to playing music (though it should still be there). Also, getting specific guests lined up in advance might be a good idea, though you should still take random callers in when you're discussing a specific issue. Basically, come up with specific times in which people should call you. This way, you don't have a million people hitting you up on skype at once unless you WANT a million people hitting you up on skype at once.
