You don't need Bonjour for iTunes. And Songbird is stuffed full of plugins and other bits. It's feature overload, but it can't even handle the basics even half as well as iTunes.

At this point I pretty much use iTunes only for tag manipulation (in Mac OS) - along with MP3Tag (in Windows). All my music is kept in a nice file hierarchy and playback is done through the best music playing software available, Squeezebox Server (which can output through Squeezebox units, the computer it's running on or any other computer).