Reads to me like the playlist route is absolutely the way to go... Why?
I would create a playlist group, call it, say, Radio.
Add a playlist for inclusion in radio
Add a playlist for exclusion in radio
Add a smartlist that includes all audio, excluding any audio in the other two playlists.
Next, create a panes based library view. The first pane needs to be that playlist group, other panes can be anything desired.
Pane tagging needs to be enabled. It is by default.
Now, the revelation...
In this view, selecting the smartlist will list music not yet reviewed for inclusion in radio. Select a track or tracks that should be included in radio.
Note the pane tagging check boxes that have appeared beside the two playlists in the first pane? Ticking one will place those selected files on that playlist.
If a file is no longer suitable for inclusion in radio, select the playlist in the pane, find the file and select it, tick the exclude playlist to add it there, untick the radio list to remove it from there.
All radio management can be right there, in one view, for example, easy creation of playlists for specific broadcasts via the "new playlist" item in the group pane.
Just a thought that sprang to mind upon reading
-marko