On my current trip, I found that opaque sites often provide the best hotel and rental car prices, but not always. And no matter how often I travel, I almost always find some surprises. My trip involved a hectic different-place-every-night itinerary, so I had plenty of tries.

>Hotels. Boston was my first overnight hotel stop, and the opaque sites failed me completely. Hotwire's lowest price for any of the districts I could use started at more than $300 a night, and I had no intention of paying $300 a night for a hotel room in Boston.

For my Priceline bids, I started with the new site,, which suggested a bid of $180 would likely be successful. But even when I bid up into the mid-$200s -- which would add up to more than $300 after taxes and fees -- those bids were all refused.

My guess is that something big was happening in Boston that night, because the opaque sites should have done much better. My fallback position? A prosaic AARP rate well under $200 at a hotel outside the districts I preferred but close enough to work.

For my stop near Charlotte airport, Priceline worked flawlessly, and I got a $95 a night room for $80. But Priceline didn't give me a good enough deal at my final stop, Warrenton Va., to offset the inflexibility, so I went with the measly 10 percent AARP discount. This time, Priceline scored on only one of three, and Hotwire didn't score at all. But that's not typical of my experience, which has generally been good with both.

>Rental cars: I needed two car rentals for this trip: for two days in Charlotte, picking up and returning at the airport, and for two days in the Washington area, picking up at Baltimore and returning to Dulles. For direct comparisons, I checked an intermediate size car -- with Avis, where prices were shown.

For the Charlotte rental, Priceline quoted $79 on its full-disclosure page, Avis quoted an AARP rate of $82, Hotwire's best opaque quote was $102, and the Avis no-discount price was $118. I tried a blind bid on Priceline that would have given a final price about $4 a night below its open price, which was refused. I finally went with the Avis AARP rate largely because of the superior liability coverage provided on the AARP program. But Priceline's open rate was very good.

For the Washington area rental, Hotwire quoted an opaque rate of $54, the AARP rate on Avis was $66, Priceline's open rate was $67, and the Avis no-discount rate was $73. Here, I went with Hotwire; Alamo provided the car.

Overall, I found several surprises in the car process:

*Hotwire's high price in Charlotte was a puzzler -- about $20 higher than Avis/AARP and Priceline's full-disclosure price.

*Also in Charlotte, when I tried the blind bid (unsuccessfully) on Priceline, its suggested bid price that stood a "very good chance" of acceptance was actually $4 a day higher than its full-disclosure price. Go figure that one.

*The rental companies' CDW (collision damage waiver) charges are out of control. Avis wanted $27.99 a day -- a rate that was actually higher than the supposed pretax and prefee base rate.

*New (to me) was the fact that Hotwire and Priceline now offer third-party primary collision coverage for $9 to $11 a day. I hadn't rented in more than two years and this one had eluded my attention. And it illuminates the degree to which the rental companies' CDW is inflated. You can bet that those third-party insurance companies are not losing money on their $9 to $11 coverage rates, so about two-thirds of the rental companies' daily CDW charges are pure gravy. No wonder they push it so hard.

For collision coverage, I still recommend relying on your credit card if you have one that offers the coverage, If not, the third-party coverages look a lot better than the rental companies' fat rates.