After staying at the Phoenix Park with my family last month, I honestly can't think of any reason why I would stay anywhere else in DC in the future.
It is super conveniently located diagonally across from Union Station, which made it an incredibly easy walk from our train.
The location also meant that it was eminently walkable to Chinatown, Capitol Hill, and the National Mall, plus both the Metro and the DC Circulator bus topped right across the street, giving us a ton of transportation options for any weather.
(We didn't take any cabs on this trip, but being right across from the train station would have made getting a cab super easy too).
The room itself was beautiful and comfortable (and a super good value for the price).
The hotel restaurant, the Dubliner, is great -- reasonably priced for DC, with very good food, good options for the kids, plenty of space, and even a great bar and live music almost every night (which we didn't get to enjoy as much as we wanted, traveling with young kids, but look forward to enjoying on a return trip).
Felt like a boutique hotel experience at a chain hotel price.
Additionally: We had originally booked this vacation for April and had to postpone with less than 36 hours notice due to a sudden death on the family. The staff (especially Robin, with whom I had several phone calls) were super accommodating, kind, and helpful and really helped make a difficult time for my family just a little bit easier.
Once we actually arrived, they again went above and beyond, helping to facilitate a room swap for our second night to better accommodate the sleep needs of our 2 year old who is going through a fussy phase.
Honestly, we got the kind of 5-star treatment that I would have expected to pay twice as much for in a city as expensive as DC.
We will be back for sure.