Hello, I love the generator! One feature I wish for is the ability to toggle population density; in smaller cities (pop below ~3000), it's not that likely that buildings would be stacked up against each other and would instead of more space. It would be awesome if we could toggle density, for instance, between (rural/urban/suburban) to get some amazing variation. Possibly rural would have a feature of densely-packed farms or something like that?

That's true - MFCG is not well-suited for generating small towns (and for very large cities, but for a different reason). It thins out buildings on outskirts and increases the size of "blocks" further away from the center effectively decreasing population density there, but these methods produce weird results when applied to the central area. I'll try to fix it somehow. For now I suggest to uncheck the "Tight" checkbox (Style > Buildings) and choose "Complex" shapes (at the same tab) - this makes a city look less congested. Or you can try to use Village Generator which has an adjustable setting for population density.