Unfortunately, Rockville does not think like Portland, but maybe imagine a vintage streetcar operation from the Rockville Town Center, to the Shady Grove Metro station and to the Gaithersburg fairgrounds—especially if the latter got rebuilt with a big modern convention center.
Incidentally, Portland's "vintage" streetcar is a replica and not original. They are available from Gomaco Trolley Company. Other cities and the National Park Service (in Lowell, MA) now operates them.
Portland also has a modern streetcar and light rail system. How do they manage that?
I know this can't happen in Montgomery County, with its and close relationship to "big oil" foundations. It only happens elsewhere.