Folks on FT (even those from "impoverished" SE Asia) generally define a "nice" hotel as one with at least 4-5 star international rating (with or without "big brand name"). You are ofcourse entitled to your own defination of "nice" which I am not disputing.

Edit : ST SIN generally goes for SGD200-250 unless its a period of exceptionally high demand . Its difficult to find a rate below USD150 for the Sheraton Saigon at any time of the year.