I was thinking more along the lines of songs (such as the early Beatles stuff) where although the lyrics might have some meaning in a literal sense, they actually don't really matter, it's the overall 'sound' of the song that does.
Personally, I'd put that sort of song into a very different category, than 'Tutti Frutti' which is pure emotion, but as you say you don't want a million sub-categories...
Another one I'd recommend for 'pure emotion' would be 'There She Goes' by The La's (to my mind the perfect pop song)
Wish I could come on your course!
Ed