Nice property, not your classical hotel
We stayed at the Eldon for two nights. The location is perfect just two blocks from the Convention Ctr / Mt. Vernon metro station on the green and yellow lines. Arriving from Reagan Airport was a short ride, probably less than 15 minutes and about 45 minutes after landing, we were already in our room. The White House is within walking distance (ca. 20 minutes along New York Avenue). As others have said, the area around the hotel is undergoing major restoration work and a new Marriott hotel is being built in front of the hotel causing some noise, which wasn't an issue for us (we could sleep without any problem until at least 8-9 am). The area is also quite empty at night, but we felt safe at any time even when coming back by metro late.
The check-in clerk was absolutely wonderful and while checking us in, he entertained us with some jokes and funny stories. He has been a wonderful source of information during our stay. Given that we booked through Hotwire, we were given a lower level room (#001). It was no problem to us and there was enough light (two big windows in bedroom and living room), but I can imagine that it may not be so funny if you had paid full price.
The suite was impressive for size and amenities including a large bathroom, a big kitchen with a table for up to six persons, a nice living room with sofa and flat TV and a separate bedroom with comfortable beds.
Summing up, we found the Eldon Suites a very nice hotel in a nice location with great prices for DC and would go back any time. Just keep in mind, that it is not a classical hotel with restaurant, large lobby area, etc, but a very functional suite complex.