Wer's option is pretty good although I'm not familiar with what tags that will and won't work with and what file types. I have mp3, acc, alac, flac, aif and who knows could be more down the road. Right now I'm moving some mp3 files so I'll give that a shot to see how it works.
You're right about "combining" would mean all that other stuff. I was just concerned about the song files and their metadata.
I tried importing a playlist, 2 times, as Brian mentions but it still doesn't add the metadata to the Library database. I'm not sure where that imported playlist is saved in the Library but it acts like the content isn't in the main database, i.e. the song metadata doesn't show up in the standard Views. I do see how playlist importing could be helpful but not for this case that I'm trying to accomplish.