We went to DC for a few weekdays last summer and we had a GREAT time!
We stayed at the Georgetown Suites, which has one bedroom with a door (not all suite hotels have doors on the bedroom), a large living/dining room with couches, a pullout bed and a table and chairs, and a kitchen with a full-size fridge and microwave. I don’t remember where we found the best deal – try all the travel sites and contact the hotel directly. We brought way too much food, including cooked noodles, pouches of tuna, cheese, rice cakes, drinks, La Bruite meals, frozen dinners (eggplant parmesan, etc – Tuv Taam and others make double-wrapped meals that can be nuked), etc.
My husband davened at Kesher Israel (aka the Georgetown Synagogue), which was a quick walk.
Our itinerary:
Arlington National Cemetery and the Women in the Military museum onsite
Night boat ride on the Potomac
Spy Museum
National Archives (we spent MUCH longer there than we thought possible!!!)
Various Smithsonian museums
Walk around the National Mall
Most of the attractions were free. There was a nominal parking charge at Arlington and the boat ride and Spy Museum were expensive but worth it.
We went to Arlington first, before getting to the hotel, then we parked our car at the hotel and took mass transit to get around. You can buy Metro SmartTrip cards at CVS – you will need one card per person.