Parking is valet and expensive. Car is a distinct disadvantage. The only other Kimpton I've stayed at in DC is the Rouge. It doesn't compare to the Monaco. I believe the latter is their highest rated property in DC. Soundproofing was an issue at Rouge. If you choose the Monaco, I can tell you what room/floor to request. There are big differences.

I was thinking more about your post. All the Smithsonian museums are a 10-20 min walk away. Think you said you have a 9 year old. Air & Space is excellent. 15 min walk. A young person would also probably like Natural History and American History (15 min the other way). White House and The Capitol are each about a 20 min away, in different directions.

For a 9 yr old the Spy Museum is virtually next door to the Monaco. A must for big and little people. Fascinating.

I seem to recall the National Gallery has a children's tour and free jazz concerts in the garden on Fridays. Newseum is 5 min walk from The Monaco, as is the Archives. All child appropriate and fascinating. American Art Museum and Portrait Gallery are across the road from the Monaco. Zoo is a short Metro ride.

This is just a short list of possibilities, to give you an idea. Lots of security everywhere and you will have to queue so time-wise that should be taken into account.

If you are interested in the new African American museum and don't have tx, possible to get them at 6:30 am daily but you need to be quick. They go in 5 min. Very worth it but exhausting emotionally and physically.

If you need restaurant suggestions, pm me. Have a wonderful trip! As you can likely tell, I love DC.