I would agree with staying at each hotel while you are in Bangkok. I love them both and Just came back from a month in Thailand. The locations are very different although you can get to both easily on the skytrain. While at the ROS go over to the Hilton and goto the top for a look at the view from the top, amazing! I stayed a the ROS the year it opened in the early 80's and it was the highest building around. Not the case anymore. Prepse to be amazed and enjoy the buffets at all the hotels.