My husband and I stayed here for 2 nights on a weekend in January. I had read some reviews on Flyertalk that had questioned my decision to stay here but I went for it anyway. We got upgraded to a Fantastic Suite - large suite with full ocean view and two (separate) balconies - one of the living room and one of the bedroom (SPG Platinum). We checked in about 4 hrs early and got our room at about 2pm which was before check in time.
We spent most of our time by the pool. The service at the pool was spotty depending on the waitress you got (one day, she would not come by at all and we had to order everything at the bar ourselves, including food. On Saturday, the busy day, we got much better service from a different waitress). Otherwise, the rest of the staff and service was great. We had no problem securing chairs with umbrellas at the pool but we arrived at the pool around 10am. By noon the place was filled up.
Breakfast was a bit disappointing - the platinum amenity gives you a $25 credit to spend at their Cafe which is just continental food (fruit, yogurt, cereal, juice and bagels). The W in Washington has done it right in that you get a credit to spend at their restaurant and often do spend more because you want to enjoy a full breakfast.
Otherwise, we found the valet and luggage attendants to be great and very helpful. I asked for a late checkout and was told I had to request it the day before departure after 6pm. I did so and was only given check out to 1pm and told to check again the next morning. I found this to be quite annoying as I knew the rooms were available (could check online). The next morning I called again and I was granted a 4pm check out which was nice - I just wish I didn't have to jump through so many hoops when I knew the availability was there.
Overall, we enjoyed our relaxing stay at the W and would consider returning for a short vacation. The rooms and beautiful and for the most part the service is great.