In D.C. proper, meaning downtown, most pool places are bars these days. Not much by way of a player's room.
Best player's room is Qball pool room. It's about 2 miles off the Washington Beltway (I-495) exit on the Maryland side of D.C.
https://www.quball1.com/
A lot of folks are raving about a new room in Gaithersburg, MD, 7 Billiards Shady Grove. It has a bar-like atmosphere but mega tables with regular tournaments. It is located at 15966 Shady Grove Road, Gaithersburg, Maryland 20877; phone, (301) 355-6177.
Street Lights Academy is the latest popular room, not near D.C. but a comfortable drive to Alexandria, VA. It's where Jayson Shaw did his straight pool run exhibition.
https://billiardsacademydc.com/
Hope this helps.