Drop-down menu or cities

I want my site to list the top things to do in 20 major U.S. cities, and I want to have a simple drop-down menu so that visitors can choose their city – similar to the one in GeoTheme.

The problem for me is that location switcher doesn’t work well because visitors cannot choose by major geographical areas – for example, a user cannot see everything in the Miami area at once – they have to choose either Miami, Miami Beach, Coral Gables, or Homestead.

Is there a way around this? It looks like from a previous post that it’s not as easy as creating a static drop-down menu. I was wondering if there was a way I could use categories or custom post types to separate listings into their correct major geographical areas?