Location, Location
With a bad back and two grandchildren in tow, I wanted a hotel that would be convenient to the DC sites. I did much research and settled on the Washington Marriott at Metro Center. I was happy with my decision. The central location was exactly what I was looking for. It was an easy walk to the National Mall, White House, Chinatown and National Aquarium. The monuments were a bit further, but the entrance to the Metro was right outside the hotel door and it took us as far as the Smithsonian which made the walk to the monuments doable (It was still long, but by walking at a slower pace my back was fine). The concierge was helpful and helped us book a DC tour of Mount Vernon (which requires transportation).
In addition, the hotel was clean and friendly. The food in the restaurant was good and offered a limited but good kids' menu. The only downside was the pool area. Although it was clean and my grandchildren enjoyed it, it was located in the fitness center and did not offer any kind of atmosphere.