Related listings best practices

I see that Related Listings can be set on the Details page for a Listing based on Tag or Category.

In my case, I’d like to have related listing based on location. For example, I have Business Listings. A business is a Category of Places. Right now I have set Related Listings based on Category. This brings up all the Places in the cateogory — in this case Businesses. Instead I’d like to have a Business Listing in a Location, e.g. New York, but for Related Listings to that Business, I want to bring up other Listings that are also in New York. These would be Places, Events, or other CPTs that don’t have to be Businesses. The “relation” is based on location (city, state, country, maybe distance).

What’s the best way to do this? I could use category and put State or City as a category along with Business but this will get very messy (all Places would have to have the full city/state/country list). Alternatively I could use Tags by putting all the City/state/countries in Tags. This is also pretty messy to maintain and requires that the people that post Listings properly Tag everything.

So, is there a better way to do this? I presume people could Search listings by City (have not tried this yet) but is there a way to present Related Listings or ‘suggested listings’ based on Location? Perhaps some “Related Location”-like feature?
thanks