Kevindoylejones, for a great overview of what can be done to design fine grain overlays on a course grain structure, I highly recommend checking out Ellen Duham Jones’ book, “Retrofitting Suburbia” (For a quick overview, check out her TED Talks https://www.ted.com/talks/ellen_dunham_jones_retrofitting_suburbia

There is no one size fits all solution, but Ellen recommends techniques like ‘re-inhabitation’—i.e. adapting big box stores into community centres or libraries; ‘re-development’—i.e. infilling in between existing buildings and on parking lots to create a more walkable, transit-served place; or ‘re-greening’ through ecological repair or to creating parks, etc.