I've noted, as a non-elite, that, at the same properties, I often get a dfferent level of room on a Priceline stay vs a paid or award stay. Perhaps, elites get more consistent accomodations because of their status. Due to this experience, I factor Priceline stays accordingly.
I've also noted, especially in the last year, that Priceline stays are becoming more problematical in certain locales and at certain star ratings. IMO, the recovery of the lodging industry has seemed to cut the dumping of rooms onto WorldSpan and, at least IME, made procurring PLN rooms at the normal 30-35% of BAR more problematical. I still look to PLN first, especially for business stays, but find I'm using it less and less, overall.
As we tend to burn our points fairly immediately, I'm pretty envious of someone with a 1.5M balance

That and Platinum status must make for wonderful adventures!
Pat