I used to live in suburban MD, outside Washington, DC. Upon retirement, I moved to DE. I visit "The DMV" and Baltimore often, to see longtime friends, attend sports, eat ethnic cuisines, and for much tourism in two cool metro areas. I use Hotels.com often. When booking my travel, I (understandably) see more expensive rates closer in to downtown. While I can usually find "deals," I check places further out.
I have frequently stayed at Linthicum Heights hotels by Marshall BWI Airport. Hotels that cater to airport traffic, but only a 15-minute drive into Baltimore. Good value.
As for DC, lately I have been using hotels near Dulles International Airport. Yes, these are further out, but well connected by Northern Virginia's extensive highways. Arlington, NW Washington are 30-45 minutes away. I have found hotel deals near Dulles, in Herndon, Sterling, or Chantilly. Often "fully refundable" when booking, with comfy rooms, free breakfast and parking.
My recent stay at Hampton Inn Washington-Dulles fit this bill. Great rate for highly-rated hotel. Comfy room. Tasty breakfast. Near IAD, Udvar-Hazy Air and Space Annex, and hotel offers shuttle to both. Lots of good restaurants close by. Other tourism attractions nearby, like VA wine country, Civil War sites.
Staff was courteous, helpful. Night reception Rebecca assisted when I called re: late arrival. Jessica cheerfully checked me in when I got there, and Kyle gave mobility-challenged me extra time on departure. Thank You!