I would highly recommend Sarah's apartment in the Logan Circle neighborhood. The apartment is on a quiet, residential street that doesn't get much traffic or street noise. There are so many great restaurants and bars within blocks of the apartment that offer a wide variety of food and experiences.
We had asked Sarah if we could access the apartment earlier than the standard 3 o'clock check in and she replied within minutes allowing us access. She was very quick to respond and very accommodating.
If you are looking for a clean, well maintained apartment in a neighborhood full of things to do I would really recommend Sarah's place.