I agree with kagehitokiri, this post should be in the thailand forum. The Dusit Thani and pan pacific are good 4 star hotels, I stayed at the refurbished Dusit Thani for one night before departure last week for a business meeting. the refurbishment is tasteful but the hotel comes no where near Bangkoks luxury hotels such as The Oriental.
However, if you are looking for a good hotel in central Silom the DT has a great location.