We booked a Club Room for our short stay in Bangkok, mainly for the city views as rooms are higher up, but what we enjoyed most was the access to the club lounge for a fantastic selection of complimentary drinks (including alcohol) and snacks/canapes throughout the day. This was just what we needed after a 12 hour flight when we really didn't feel like venturing out into the busy streets of Bangkok. Club rooms also offer 1 piece of laundry cleaning per night which we made use of. Would highly recommend paying the extra for a club room.
The hotel is well located for the street markets and Siam Square, with a metro station right outside the entrance for access to other parts of town - we used this to get to the river for a boat up to the main temples of Bangkok.
We sat by the pool one afternoon which is on the top floor. Although not open air, the sides of the building are open. The pool area is very clean and modern. I didn't swim however as found the water too cold. It was also quite noisy as the street and construction noises can be heard from the city below.
The rooms are of a high quality - luxury bathroom with bath as well as dual shower (wall attachment and rainfall). My only gripe would be that the hotel walls seemed very thin - unfortunately we had a noisy family in the room next door who we could hear very clearly. However, the hotel were very good at contacting the family and asking them to be more considerate which seemed to do the trick!
All in all I'd say this was one of the top city hotels I have stayed in and would highly recommend, echoing all positive comments beforehand.