IMHO, Priceline USED to be a great resource for Thailand, especially Bangkok, but it no longer is. 4-8 years ago, there were only a handful of 5* properties, and they were all TRUE 5* properties, that you could get with Priceline. In those days, I booked my first 2 visits to Bangkok on PL, and got the JW Marriott in Sukhumvit, and the Shangri-La on the river, each with $73 bids. Using other venues would have resulted in rates around $150/nt for these places.

But nowadays, there are several much more marginal 5* places, especially a couple of Amari hotels that are really more like 4*s, that have ruined Priceline as a source of true bargains. Those Amari properties can be booked elsewhere for roughly the same prices that they come up on PL, but they effectively preclude getting the better deals at the genuine 5* places. Occassionally, one can still get a deal with one of the Marriotts or the Plaza Athenee, but one is always flirting with the likelihood of "winning" the Amari Watergate or Amari Boulevard instead nowadays.

Nowadays, I use Agoda for all of my Thailand bookings, except when I am staying on an SPG points stay.

BTW, there are now TONS of new boutique and 4-5* hotels in Bangkok that have a glut of rooms that are offering deals - but Priceline is not the venue to get them, Agoda is a good choice.