Personally I find good terrain makes for a better game. When developing this setting for a campaign I always had in mind the type of architecture and the personality of the city of Lewiston.
Lewiston draws a lot of inspiration from other American cities, mainly Chicago and Seattle. Lewiston has a similar general architecture like Chicago, rains and has many surrounding mountains like Seattle.
Because of the popularity of zombie miniature games there is a wide variety of Chicago style buildings available. Here is one I have managed to assemble and paint.
There are quite a few companies that make good MDF terrain, Sarissa- Precision, TTcombat and 4ground. All of which have a place in Lewiston.