My wife and I are planning travel between NY and DC in July and I'm looking for feedback for those that know the area well. We have not booked hotels or flights yet and are open to thoughts on whether to start in NY and work our way South or vice versa.

The idea is for this to be more of a U.S history trip with some church site(s) sprinkled in. We've got 7-9 days available. What are your recommendations of must-see sites to see in addition to what I've captured below?

Any other tips are appreciated!

New York:
Palmyra
Niagara Falls
NYC

Pennsylvania:
Philadelphia
Valley Forge
Gettysburg

Maryland:
Baltimore

Washington DC:
Smithsonian Museums
White House tour
Capitol Tour
National Mall
Library of Congress
National Archives
Mt Vernon
Ford Theater