Sorry for reviving this thread a month later but I had pulled it up looking for info on Travelocity Top Secret Hotels after the fact.
Empirically, I agree that we've always had "better luck" with Priceline than Hotwire and essentially end up using Hotwire as a basis for our bid strategy/upper limit with Priceline.
However, question: If Priceline, Hotwire, TTSH, etc don't have the same stable of hotels, is it really an apples to apple comparison to say "No one beats Priceline" (while keeping in mind, I'm looking for the cheapest price based on expected amenities/parameters for a star level and obviously being fairly flexible on the actual property I end up with).
Case in point, we recently bid for a place a week and a half out: Hotwire was showing ~$60+ for the areas we wanted to stay in (just checked again today and still shows similar pricing). We bid up to $50 in equivalent areas via Priceline with no luck. Used TTSH's and won a place for $45. Hotel was not listed as a known hotel for Priceline (but surprisingly with Hotwire with same star parameters).
I suspect our recent TTSH purchase was likely more of an aberration but I'm curious if there was anything going on behind the scenes to allow this to happen (eg. Travelocity working some undercutting somehow, etc??).