I strongly advise travellors to avoid Grand Mercure Bangkok for following reasons:
1. What you see in the photos is NOT what you stay, especially some of the deluxe rooms have not been renovated at all and feel entirely old (1-star?). This is very dishonest because we get an impression of the hotel in pictures that is far from reality.
2. They confirmed my internet booking but on arrival were unable to provide the non-smoking room reserved and put me in a smoking room on a smoking floor. They offered NO REFUNDS even if I wanted to change hotel.
3. They promised to move me to a non-smoking room the next day, even told me the new room number -- but the next day they gave that room to another customer and told me to stay in the same room as the hotel was fully booked.
4. The staff were unable to DO anything except apologize which gets very irritating after a few sorries with no solution offered.
5. I have stayed in hotels all over the world for more than 20 years from 6-star to budget hotels, this is by far my worst impression. I would expect far better from the Accor Group.