Thanks for the invite and the kind words Joy.
Cases like this are hard. I don't have the answers for you.

But I can give you my thoughts.
The company that was doing SEO before us literally built out more than 900 pages targeting one keyword in one city.
Ouch. The sad thing is that this type of thing used to work really well. I'm working with a client right now that used to rank really well for almost every city in the US based on almost identical pages that just swapped out the city name. They got a thin content penalty and although they are no longer manually penalized they never really have recovered.
So of course this client wants to regain those rankings, but is it possible? I think it *is* possible but not using the methods that used to work.
In the past we could build keyword rich location pages and build links to those pages and it often could work extremely well. So now what I see people trying to do is recreate those location pages but try to rewrite them so they have original content. I've yet to see that work. When Panda first came out I think we got so fixed on duplicate content that we thought that just having a page that passes a copyscape test would fix everything.
I am thinking more and more that as Panda evolves it is using machine learning to truly determine whether a page is best for users. Google wants to rank the pages that users want to click on.
So, let's say I had a fictitious company that sold green widgets online and I want to rank for every single city for people who are searching for green widgets. In the past I'd create a page with a title tag of "Buy green widgets in Orlando" and optimize the content of the page for Green widgets in Orlando. And then I'd repeat that for every city I wanted to rank in.
But now, let's put ourselves in the shoes of someone who lives in Orlando who is looking for green widgets. Perhaps green widgets are something that local stores like Home Depot and Walmart sell. Or perhaps there are green widget specific stores right there in Orlando. Am I going to be able to convince Google that my website that doesn't even exist in Orlando (but ships there) should outrank the big box stores and local vendors? That's going to be hard.
In my opinion, the only way that I could have a top ranking locally is if I could convince local searchers that my site is by far the best option for them to view. I think there are a few ways that I could convince users (and then Google) that my page is the best:
-Perhaps if I have a massive brand presence. For example, Amazon doesn't have a local office in Orlando, but people recognize the brand and want to buy from there so it might possibly get good rankings.
-Having EXCEPTIONAL content. And I mean exceptional. And that's hard to do. If the top ranking pages for green widgets in Orlando all have the basic information on price and availability but my page has loads and loads of information I might be able to rank better. I could have pictures of my products being used in Orlando, instructional PDFs, videos, guides of which green widgets are the best to buy for Orlando residents, and so on.
OK, so this is a long answer.
Back to the original question:
This client wants to rank for more than 200 cities in more than 10 different counties. After looking at the competition and seeing what they were doing, we decided the best plan of action was to create county pages and mention the cities serviced at the bottom. Instead of having nearly 1000 pages trying to rank for specific search queries we are condensing them into 10 pages that go in-depth on the services they offer.
That's tough to answer without knowing more about your client. If they truly have a share of the market in all of these cities, it might be worthwhile to create fantastic pages for all of them. But, if they are trying to rank for something where it is unlikely that users would want to click on their site rather than the ones that are already ranking, it might make sense to do it the way that you suggest. This should capture the brand searches. (i.e. people searching for brand+product) in that city.
I don't have a definitive answer though and am looking forward to seeing how others do this.