There are more than 4 suites in the Author's Wing, and I have stayed in three over the years, but I would not recommend any of them - furniture is dark and cheap and generally there is no light in these suites. They all need a major rethink.
The Garden Wing Suites are very cute but extremely small - bi-level with tiny bathrooms and a sort of sleeping platform - very popular with honeymooners.
The River Wing has the best suites. The 2-bedroom Oriental Suite is extremely spacious with amazing river views from balconies on 2 sides. Some of the smaller suites are a bit dingy and overly eccentric. Difficult to say which is best as they re-decorate every so often, so what I remember of some suites in this wing may not be true today. It really depends upon what style you prefer - very Thai, very Barbara Cartland? I would ask the hotel - tell them what you are looking for and get them to help - that's why they are here.