Multiple Keywords Content Generation SEO Strategy

I believe your understanding of the SEO problem you are having when trying to rank for multiple city keyword modifiers is superficial. There are two components to the SEO puzzle, optimization of the on-page elements and of the off-page elements, from which the latter has far greater weight when it comes to rankings, meaning that the relevance of the page is mainly calculated based on inbound links. Having inbound links from websites relevant to the city in question will get you good rankings coupled with that city keyword present in your page title, headings and body text.

On-page, IMHO, the best way to approach the city keyword modifier problem is by having a combination of static and dynamically generated content so that you have an individual page, optimized for each city you are trying to rank for. However you will have to come up with a decent size content that is unique to that page. I think you can try some UGC like comments from Miami buyers or a google maps app or anything else you can think of.

There is a not yet proved theory about google relevance calculating algorithm that says the occurrence of terms correlated with the main targeted term helps rankings.

But what I can tell you from my own experience is that for ranking on terms ending in NY you have to have inbound links from pages with the NY keyword in them at least, if not better in the anchors of the link to your website.

While having a dedicated page will always be good as long as each page's content can be sufficiently unique, which is difficult to do over a large number of long tail terms, you've got to first look at the competition for the key terms you wish to target. If the terms are not too competitive and very long tail, then you could consider just optimizing the current set of pages to have those target terms in them and focus more on building links to those pages with the targeted anchor text. If the terms are reasonably competitive, then you'd want dedicated pages or even domains in certain cases. It really depends on the competitiveness of the target terms.

I would always look at what the other sites are like that are ranking for those terms and try to come up with a strategy, that while similar, will be slightly better in terms of execution of it's content and link building strategy.