Hi, Rory.
Great post!
Hear, hear, to Mark's comments!
I've done a lot of sleuthing in US and NYS census data, manually transcribing data that Ancestry.com doesn't automatically handle. I've also relied on the many editions of the Buffalo City Directory for the late 19th and early 20th centuries to piece together movements of my ancestors. All this work entailed handling snippets of data, while you on the other hand have dealt with the problem whole cloth!
In the past I thought about taking one residential neighborhood and compiling a history of it from census data. Your tools could make this dream a reality.
Ah, a thought just occurred to me to help you along with your novel. Look at some news papers from the period and study the advertising.