Well, if I were in Bangkok, I would have chosen Sukhothai over the four seasons. The Sukothai is famous to offer a quiet and relaxing experience. If that's what you want, then go for Sukhothai. Also, it is a member of the leading hotels of the world.

For the comment about the Peninsula, I agree that their service is great and nice river view. It is cheaper than the Oriental across the river as well. The Peninsula Bangkok has been voted the best hotel in the world by Travel and Leisure Magazine. It is also a member of the Leading Hotels of The World. The price is very reasonable too. I don't know your exact day of arrival, but a room from 12/22 to 12/23 runs from USD 190.00 per night.