For a very good experience at far less money: Hotel Berkeley Pratunam.
Great Central Location. It's even walkable from the Ratchaprarop Station on the airport express rail link.
Small-ish night market next door with good seafood bbq options.
Take the Klong ferry to Jim Thompson House.
Walking distance to Central World, SIAM, MBK shopping
In Centralworld, I highly recommend eating at Kum Poon. Hip, modern interpretation of traditional provincial Issan recipes.