Having stayed at this property several times as a previous Platinum, a couple of notes:
1) You will have access to open-air lobby lounge as Platinum - count on it.
2) You will probably not want to have breakfast at the lounge but instead at the cafe downstairs - more choice. As Platinum, they will extend to you this benefit.
3) I've been on the Manohra cruise - delightful experience. I think I paid 1000B/person a year ago (hosted a party of 4)
I would not book the US$220 suite = $100 (x 2 nights) could buy you plenty in BKK. You would get upgraded anyway to a nicer room besides the standard room - IME this property treats Platinums very well
Whether you stay at this property depends entirely on whether you like serenity (the lush gardens are very nice at the Resort esp. when it rains at night - gorgeous) or easy transport access (JW is a 5 minute walk from the trains while the Resort is a boat ride away from mass transit) and in rush hour, quite a feat to get to by taxi. Also the bathrooms of the Resort is a let-down because there is no separate shower and the half-length shower pane in the bath tub results in wet floors (at least for me).