For a handful of different locations, it's quite common to structure them as different subdirectories, as you said. site.com/weddings/miami/planners or /miami/weddings/planners - whichever makes the most sense for your customer base and how you're targeting the content.
Just ensure that these are not considered doorway pages or appear to be too templated. Make each landing page for each location unique, and tailored specifically to your customers in each location. If you have nothing unique to say, then you don't need separate pages. It would be best to target the different locations on the same landing pages. But you being the expert in the industry, I can imagine it'll be easy enough to cater toward each audience specifically. Especially when you're not dealing with tens if not hundreds or thousands of different towns.
If you are certain on expanding to different cities soon, then it might be best to begin the URL structuring with /washington-dc/ subdirectory somewhere, so you don't have to change this later.
