Chino Valley? Not Really
Now here's an example of a business that changed their name as their geographic coverage increased: Citizens Business Bank. They were formerly known as Chino Valley Bank, but they spread beyond Chino Valley and went toward a business focus.

"Currently, the Bank serves the business banking needs of business people in the Inland Empire, Los Angeles County, Orange County and the Central Valley areas of California."

So, perhaps Century 21 Beachside should change its name. Here are my suggestions:

Century 21 Locals and Non-Locals Only
Century 21 Beachside and Desertside
Century 21 Southland
Century 21 Wipeout (Surfboard or Dragstrip, it's up to you)