Great hotel - great location
We stayed at the Park Hyatt for four nights over summer with our two teenage sons and found it a great base for all our DC activities. The property offered fantastic rates as the Senate wasn't sitting and was very accommodating in meeting our request for two adjoining rooms - so we were delighted when one of the rooms was upgraded to a suite. 
The rooms were spacious and very well presented and the bathroom in the suite was exceptionally stylish. The toiletries were lovely, which was a bonus. The service was efficient and friendly at all times and the concierge was very helpful in providing advice on transport and attractions, particularly given our stay covered July 4 when many streets were blocked off.
Yes the bar is a little pricey as are the laundry charges, but that's just five-star hotels generally. Well worth it for the superior rooms and service. And the location is great - a short stroll to the Foggy Bottom metro if you want public transport and a very easy walk into Georgetown for great restaurants, cafes and shopping. A winner!