Sorry, I didn’t read the entire thread, so a lot of this may be duplicative, but I’ve lived in the DC area for 15 years, and here is a list of things I always send to friends/family who reach out about visiting DC. I also included helpful tips about what locations require tickets (mostly free, but timed) so you don’t get shut out somewhere – especially in the summer time.
Walk the national mall – you can see all the monuments. Capitol building, Washington Monument, Lincoln Memorial, Vietnam Memorial, Korean War Memorial, World War II Memorial, Jefferson Memorial, The Reflecting pool, FDR Memorial, MLK Memorial. Also a great place to run if you’re a runner. Doing this is also fun at night. The memorials have totally different feel at night when they are lit up.
Smithsonian Museums (on the national mall) – American History, Natural History, Air & Space, Native American, African American, The Smithsonian Castle. (There is also an Air & Space Museum extension at Dulles Airport that has the really big planes – it’s worth the trek).
Holocaust Museum – (get advanced reserved tickets if going in the Summer). They are free, but they limit the number of people that go in at a time.
National Archives – just off the national mall on Constitution Avenue. Again, get advanced timed tickets if going in the summer. You can wait in line for an hour or two if you don’t.
Capitol tour – get in touch with your congressman or senator. I recommend both, as you will likely get a chance to meet them.
Library of Congress – one of the most beautiful buildings in the city. Highly recommend touring it. Again, get advanced timed tickets in the summer.
Supreme Court – recommend trying to tour if you get a chance.
The White House – I believe they are doing tours again (closed during Covid). I think you can get them through the WH Visitors center (in advance) and possibly through your congressman.
Arlington National Cemetery – Must see in my opinion. See the changing of the guard at the Tomb of the Unknown Soldier (done every 30 minutes in summer), JFK’s gravesite, Audie Murphy’s gravesite (most decorated WWII soldier – it’s near the Tomb of the Unknown Soldier, and the Lee Mansion.
Mount Vernon – George Washington’s Home. It’s a bit outside the city, but absolutely worth the short trip (a Cab or uber can get you there). Can tour Washington’s home, walk the grounds, see his tomb, and the view of the Potomac River is fantastic. If you’re coming near the 4th of July, they do fireworks over the river. Get tickets when they go on sale as they will sell out. My wife and I are members here and go frequently, so I highly recommend it. Also, do brunch at the Mount Vernon Inn. It’s very good. Make a reservation in advance. You can also tour his distillery during the summer (advance tickets and dates) and can get Rye Whiskey that is made using his exact recipe and formula – can get this in the gift shop as well. He was one of the largest whiskey distributors in the US after his Presidency.
National Zoo – it’s an ok zoo frankly, but I’d put this way down on my list. Omaha and Minneapolis zoos are better – especially now that there is no Panda at the National Zoo anymore.
Georgetown Waterfront – lots of nice restaurants there (not the cheapest, but fun place to go). Just walking around historic Georgetown is fun too. Georgetown cupcake is here (although it is more of a tourist stop). JFK and Jackie owned a condo in Georgetown when he was elected a Senator. She also moved to Georgetown after he was assassinated.
Ford’s Theatre – Theatre where President Lincoln was assassinated. You can tour the theatre, the museum below (which has the actual gun Booth shot Lincoln with), and the house across the street where Lincoln died. Again, get advance timed tickets in the summer. My wife and I are also members here, and it is worth the visit.
National Cathedral – beautiful building. Recommend touring it.
St. John’s Church – across the plaza from the White House. Virtually every President has attended church here. Some, including Lincoln, regularly. I believe there is still a plaque in the booth where Lincoln sat each Sunday.
USMC/Iwo Jima Memoral – in Rosslyn. Really cool. They do Marine band concerts there during the summer for free. Check the schedule (last I knew they were Tuesday nights)
The Pentagon – You can see the 9/11 memorial near where the plane struck the Pentagon. I don’t believe there are public tours of the Pentagon itself.
Roosevelt Island – Off the GW Parkway, you will likely need an Uber to get here. Can walk around the island and the Teddy Roosevelt Memorial is on the island.
St. Matthew’s Cathedral – where JFK’s funeral took place. I believe there is still a plaque on the sidewalk where JFK Jr. stood to salute his father’s casket.
National Gallery of Art – near Chinatown. They have lots of cool historical and other paintings.
National Portrait Gallery – Near Chinatown as well. Very cool
US Botanic Garden – very pretty in the summer. On the national mall.
International Spy Museum – just reopened a few years ago in a big new building. Note, this museum does charge for admission.
The Kennedy Center - Great place to visit. The view of the Potomac from the roof is gorgeous. They also have a roof top restaurant (will need a reservation). Also, see a show here. There are plenty of ticketed events, as well as free concerts in the concert hall. Check the website for the schedule.
If you’re coming in summer, I also recommend catching a Nationals game at Nationals Park. The team isn’t very good right now, so tickets are not expensive. It’s a fun atmosphere and you will get to see the “President’s Race”. The club has 4 Presidential mascots – Washington, Jefferson, Teddy Roosevelt, and Lincoln. They roam the park and do a race mid-game. Great if you have kids.
As far as food goes, there are so many restaurants here that you can find any type of food that you want. I do recommend Old Ebbitt Grill – near the White House. Has been in business since 1885. It is a DC icon. Get a reservation, especially in summer! Again, just search online for whatever types of food you’re looking for and you will find it. I’m happy to help with any specific requests!
For transportation – I highly recommend Metro. It admittedly is less reliable than in the past, and the hours have been reduced some due to “budget” issues. But it’s still, by far, the best way to go if you’re visiting the city. I recommend trying to get a hotel, Airbnb or Vrbo that is within easy walking distance of a Metro stop. It will make your life MUCH easier.
I know that's a LONG post, but happy to help. Anyone wanting to do DC, always feel free to DM me! Happy to help fellow Clones any way I can.