I'm using my Royal Orchid Plus (Thai Airways) miles to book a hotel in Bangkok, but I can't decide which one has the best amenities. I usually stay at the Watergate/Erawan area so I would prefer a hotel there, but I'm open to staying elsewhere that has good access to the Skytrain/ subway and a mall.

Anyway, I've narrowed down my options to the following:
Grand Centara at Central World (I heard the rooms are small?)
Novotel Bangkok on Siam Square
Dusit Thani (I heard this is a good hotel, but I'm not too sure about the location and accessibility)

Any suggestions? Thanks!