"Like many American cities, Washington didn’t have one single prominent church, since which one you considered important tended to depend on the denomination you belonged to."
That is arguable, I suspect that there is _one_ church in DC that most reasonably well read Americans will have heard of or seen mentioned on TV or in the news, namely the "Washington National Cathedral". Its also been mentioned or used in many TV shows, movies and novels.
Note Gibbs' reaction to hearing about number of churches in SunnyHell, along with the number of cemeteries there.
So I wouldn't have been too surprised if he looked for Dawn at the Cathedral rather than at Arlington.
Technically its a Episcopalian Cathedral, but its effectively the US's National Cathedral, note all the funerals, memorial services and other special services. See below.http://en.wikipedia.org/wiki/Washington_National_Cathedral
National House of Prayer
Congress has designated the Washington National Cathedral as the "National House of Prayer". During World War II, monthly services were held there "on behalf of a united people in a time of emergency". Before and since, the building has hosted other major events, both religious and secular, that have drawn the attention of the American people.
The 2004 state funeral of Ronald Reagan
Funerals for three American Presidents have been held at the cathedral:
Dwight Eisenhower (1969): Eisenhower lay in repose at the cathedral before lying in state
Ronald Reagan (2004)
Gerald Ford (2007)
Memorial services were also held for presidents Warren G. Harding, William Taft, Calvin Coolidge, Harry S Truman, and Richard M. Nixon.
Presidential prayer services were held the day after the inaugurations of Franklin Delano Roosevelt in 1937, Ronald Reagan in 1985, George H.W. Bush in 1989, George W. Bush in 2001 and 2005, and Barack Obama in 2009 and 2013.
Other events include:
Funeral for former first lady Edith Bolling Galt Wilson (1961)
Memorial service for former first lady Eleanor Roosevelt (1962)
Memorial service for the casualties of the Vietnam War on November 14, 1982
Public funeral for Chief of Naval Operations Admiral Jeremy Michael Boorda (1996)
Funeral for Secretary of Commerce Ronald Brown (1996)
Funeral for U.S. Ambassador to France Pamela Harriman (1997)
Funeral for Washington Post publisher Katharine Graham (2001)
Memorial service for the victims of the September 11, 2001 attacks
Special evensong for the victims of the Virginia Tech massacre
Funeral for educator and civil rights leader Dorothy Height (2010)
Memorial service for NASA astronaut and first man on the Moon Neil Armstrong (2012)
Funeral for U.S. Senator Daniel Inouye of Hawai'i, President Pro Tempore of the Senate, and Medal of Honor recipient (2012).
It was from Washington National Cathedral's Canterbury Pulpit that the Reverend Martin Luther King, Jr. delivered the final Sunday sermon of his life, just a few days before his assassination. A memorial service for King was held at the cathedral later the same week.
I stand by the words I gave Gibbs- what church in DC a person considers important is not clear cut. Washington is not a European city, where most people would think of one particular church or cathedral. There's even more than one cathedral. (Kennedy's state funeral was held from St. Matthew's Cathedral- because he was Catholic, so it needed to be held at the Catholic cathedral.)
Also, even if Gibbs had focused more on churches, the Washington National Cathedral is not particularly walkable from anything other than its own neighborhood. Xander told Gibbs Dawn was someplace she could walk to from where she was dropped off. Unless they were coming in from one or two specific neighborhoods, I'm having trouble picturing how Gibbs would come to the conclusion that Dawn would have been somewhere in walking distance of the cathedral.