I agree with SmilingandDialing.

Priceline does not give you the option of upgraded rooms or anything like that. Also, when looking at these properties in prime real estate, there tends to be a fairly small difference in points required between an ordinary hotel and a top-quality one - using New York as an example, between the Hilton Garden Inn and the Waldorf-Astoria.

In my case, I have booked almost every hotel stay for the past 7 years on Priceline, but for my own honeymoon (next month) I accumulated a pile of Hyatt points to stay at the Park Hyatt Vendome in Paris (partly on points, partly on Hyatt card nights). But I could have gotten a 4-star hotel in the same areas of Paris for $175 a night.

If you don't want to cope with the bidding process on Priceline, you can use Hotwire for an easier process but a somewhat higher cost, but still (usually) significant savings.