Anyone have any experience with either the Capitol Hill Hotel or the Phoenix Park Hotel in DC? Both look interesting and close to everything.

We stayed at Hotel Monaco. Very convenient to Mall, downtown, Archives, etc.

both are "nice" boutique hotels and near the Capitol. I used to live on Capitol Hill and had my family stay at Capitol Hill Suites, only because it was closer to my house. Depending on what all you are doing, the Phoenix will most likely be more conveniently located - near the Senate office buildings, Union Station and many restaurants.