Customer service at the Park Hyatt is outstanding!!
My wife and I recently visited DC for our 30th anniversary and stayed at the Park Hyatt. I chose the Park Hyatt because of the many favourable comments posted on Tripadvisor and I must admit they were bang on. The Park Hyatt staff understand what customer service is all about ... whether it was the front desk, concierge, bell men, housekeeping or the restaurant ... the service was excellent. The friendly staff made you feel welcome and they treated us as valued customers. As a nice touch, the front office manager sent us a bottle of champagne for our anniversary. We were particularly impressed with the concierge who would greet us by name as we walked through the lobby.
We stayed in a Premier Deluxe king room and it was spacious, clean and very comfortable. The bathroom (with its rainwater shower) was very impressive. Our room was located away from the main street so it was very quiet. The hotel has a fitness club and an indoor swimming pool. My wife used the pool a couple times and it seemed like her "private" swimming pool as it didn't seem to be heavily used by other customers.
The hotel's restaurant (Blue Duck Tavern) is very nice. As part of our package, we had a daily complimentary breakfast at the restaurant and it was a great way to start the day. We also ate dinner at the Blue Duck one evening and the food and service was excellent. 
The hotel is located in a very nice neighborhood near Georgetown and is close to shops, etc. We did a lot of walking in Washington but did take advantage of the complimentary sedan that the hotel offers.
The Park Hyatt is a 5 star hotel so it is a little expensive, however, it's good value for your money and was a great "treat" for our vacation. I would highly recommend this hotel to others.