@mfherman shoot, actually this won't work for the time-series data I'm using. It works with geom_point, but with time-series and geom_line, all of the individual 'other' items get lumped together into 1 line.
Leaving this thread as 'solved' because it solves the example with geom_point. I'll have to create a new post with a better example.
Edit: Created new post here: ggplot - how to show individual observations with geom_line but group their color?