My stay in D.C was perfect. Grace his sister (co-host) have been very welcoming to me, and helpful.
The house is in a secure residential location in a safe neighbourhood close to the subway leading straight to downtown, in about 15min. There are shops not so far. 5-10 min walking.
The house is big and super quiet, have access to the whole kitchen to yourself, living room, washing machine. Etc ... It feels just like home.
From union station to the house I paid 7$ with Uber. I do recommend this place.