Using play lists, I came up with a pretty good solution. I use windows media player to sync music so I added my audio folder to it's library.
I then made an auto play list called ALL Music and set some rules including "Album artist is Not ..." I did that for all my non-music audio files. So I can use that play list when ever I want to listen to music. I then made more auto play lists for each set of audio files with a rule like "Album title contains pimsleur" for example.
All this syncs to the phone so I can just click on what ever play list music or pimsleur, etc. This works fine but I'm still surprised there isn't another folder we can access called other audio or something so we could keep it totally separate from music. By the way, the podcast store on windows phone 8 seems really nice. I found lots of good audio shows to subscribe to.