Just my $.02, as I started a similar thread in the Online Booking Forum. I have spent nearly $3000 on Priceline int he past few years, but

with the lack of bonus money,
increased discounting by the hotels themselves,
poor customer service from Priceline if there is a problem,
'problem' hotels more and more often slipping into ratings (such as Holiday Inn or Best Western's as 3*),
not a lot of availability at smaller locations,
not a lot of information on smaller locations at either BFT or BetterBidding,
the lack of elite benefits,
combined with the predisposition to be treated somewhat worse as a Priceliner,

I have not booked a Priceline hotel stay in nearly a year. I figure I pay about $20-$30 a night and get flexibility on cancellation along with choosing my hotel. Worth it for me, but I guess if price is still your only concern, Priceline is the way to go.