I wasn't sure how to use \with in the Score context, for some reason it didn't occur to me that I needed to \new Score instead of just \score ...
Is there a list of stuff that can be put into \with somewhere?
Actually, to be honest, I think something like that list would be useful in any context; a list and brief description of commonly-used parameters for each block or whatever. It's probably quite an immense time commitment, but I would argue that it'd be well worth it. I just don't know enough LilyPond to make myself useful in creating it.