I am looking for a way to code a field that contains differents sets of dropdowns for the same field contingent on other field values.
For example, if a user chooses 'New York', I'd like the dropdown to contain: Empire State Building, Brooklyn Bridge, Wall Street; if the user chooses Orlando, I'd like the choices to be: EPCOT, Universal Studios, Animal Kingdom.
It sounds like you're referring to a Dynamic Data Retrieval rule. You can poplulate droprdowns dynamically, either using the rule actions or your own SQL. There is information about and instructions for configuring these in the Active Form Components Guide.