I've stayed there on business a few times after previously having lived and worked in DC. First off, it is a very nice, very expensive hotel. My business rooms, rack rate, are probably $500/night. Aside from that, there are three reasons I would not take my family there. One, it is a (high-end) oriented business hotel. I've never seen a family there. Ever. Two, it is located 15 feet from old school train tracks that are well used all hours of the day. This is highly unusual for DC, and can keep some people from getting decent sleep. While it's technically close to the Tidal Basin and the Smithsonian area, on the other side it gets industrial very fast. Finally, it's not far but neither especially close to a Metro stop, which is the lifeblood of DC transportation.
Since I'm guessing point trade-off isn't very good, I would recommend pretty much any hotel in Rosslyn. This is barely across the Potomac ( you can walk across the key bridge into Georgetown) and also right on the blue and orange line metro. Your money will go a lot farther here and the location is actually better than the Mandarin for moat DC stuff.