Jessy, we always fly a US carrier to BKK. It's much cheaper. I was advising on Thai internal flights. You should book air to BKK as soon as possible.

On the ROS, we always stay there and like it. While it's not very Thai, it is convenient and the pool is quite good.

kathie has hit on what i did not like...
i do not find it has any thai flavor at all....i found the staff on several occasions to be non-interested in customer service...
the location is good but not excellent...access to the skytrain is the least good of the major river hotels...
during our stay, we had two instances of strong fumes in our room and on the last day it was so bad that we had trouble dealing with it and getting out without getting sick...i spoke to the staff and they again were disinterested....there were other people also at the desk complaining...

kathie is correct....many fodorites like their stays there...

i find the sheraton grande on sukhumvit to be a far nicer and more lux hotel....only problem is that it is not on the river...

in short i guess i just find the ROS boring and just another hotel...nothing special...

for less money the marriott is a far nicer hotel in every way, imo..

we all have our favorites...