For New York City FC away days, Washington, DC is kinda perfect. Think of it this way: a lot of casual fans are more than willing to make the trip to Harrison for the Hudson River Derby. That can dilute the atmosphere just enough that it’s noticeable. Same-same but different for trips to Chester to take on the Union; it’s still too easy a trip to screen out those who look at such a thing as more of a curiosity than a way of life.
DC ain’t that. Six hours on a bus is manageable, but enough of a commitment that only the diehards are likely to pull the trigger, go wild, bang drums on the way down, and cheer on the Boys in Blue like lives properly depended on it.