Great location - not a great stay
I lived in DC the past 5 years and very familiar with the city. I moved away and came back for business and booked through Priceline. The St. Gregory came up and the location is very convenient for downtown/West End. Upon arriving, the front desk was very helpful and pleasant, allowing me to leave my bags while I waited for my room (they did not have early check-in that day). Parking was also reasonable at $35 for the full day and night. When I returned to the hotel to check-in, the front desk could not locate my bags. After searching multiple rooms for about 10/15 minutes, they finally found them. There was only one person working the front desk and there did not seem to be any procedures in place.
The lobby is nice and the hotel bar/restaurant has a great brunch. The downside to this hotel was the room. The bathroom is somewhat updated, but the door to the bathroom barely opened up without hitting the sink (poor renovation at best). The shower faucet was loose and overall condition was not the nicest for a hotel classified as a 4 star. The room was poorly lit with no natural light and old floor lamps. The room (I think it was #214) backed up to the service corridor so I woke up to trash/delivery trucks at 6AM. The overall condition of the room was outdated and looked like it had not been renovated since the early 1990s. 
Overall, I would not recommend this hotel if you are looking for a higher-end place to stay for business or leisure. Hopefully they are planning to renovate all of the rooms soon, since the location is ideal.