I stayed here in March and had an amazing experience. I'm SPG Gold and paid for a Studio Suite using a B2G1 free promo which made it only about $30 or so a night more than the standard room.
I check in on a Friday night and found that I got upgraded to a Marvelous Suite with a complementary bottle of wine waiting in the room. Not bad for a low-level SPG elite like myself!
Kinda off topic but I've found most hotel rooms in BKK are either blazing hot or ice cold, nothing in between. I've stayed ~30 nights at the BKK aloft in the last two years and still can't figure the aircon out.