If you're not part of the soultion...
You're part of the precipitate!
Dawned on me one day if occupations would work for Surburbia when I noticed Dale Yu's contributions who also contributed to Agricola.
The main downside being the luck of getting an occupation related to a goal, or the appropriate tiles not coming up related to your occupation in the game. But assuming if you could play an occupation instead of a tile, that can give reason to add more tiles in. And perhaps as an action you can "enable" a certain goal, a la Terraforming Mars. Thus allowing a few more tiles to be added.
Ideally I would think Occupations, or assistants would fit thematically, and could work the same way, with pre-requisites, possibly a cost, and active or passive abilities.
Derrek, I have already thought about this in the past - but we couldn't make it work. I might try again at some point, but we've got other exciting expansion ideas on the horizon that we're currently working on