Think you're a savvy traveler? Well, here's a pop quiz. Which is the best hotel deal: One that delivers (A) 50% off your second night, (B) your fourth night free, or (C) 30% off your nightly rate? Go ahead and get a pen and paper. Or a calculator. Or a fifth grader. We'll wait.

For travelers in this dismal economy, there's been a silver lining: Super hotel deals, and lots of 'em. But those deals are dreamed up by hotel marketing teams who crunch numbers and write catchy headlines for a living. And that's exactly why you need to do the math before reaching for your credit card. Sometimes you won't save quite as much as you'd think.

Take the "Better Tomorrow" promotion that's on the table until March 31, 2009, at  Starwood Resorts (which includes W, Westin, St. Regis and Sheraton hotels). For every night you book, you get 50% off the next night's rate. Wow, 50% off! That sounds unbeatable, right? You can put your calculator away now. Michelle Deal-Zimmerman, the very wise travel editor at the Baltimore Sun, has done the due diligence for us.

"But here's a problem that I did find when I eagerly began plotting my holiday stay at Starwood's new Resort at Singer Island in Palm Beach. (Yes, as usual, I'm headed to Florida for Christmas. Why? Because I have a mother who knows how to use a cell phone and guilt.) I found three different rates for three different specials for four nights during the same week.

Starwood's "Better Tomorrows" special would cost me $867. Their "Winter Sale" offers a 30% discount and would cost $688. They also have a "4th Night Free" special - the word "free" is so enticing - which would cost $1,067. The last two specials I checked for the very same dates. So you would have two guests staying the same nights, with one paying $400 more and both thinking they got a deal."

So the correct answer is C.  A 30% discount trumps "fourth night free" (which is essentially a 25% discount) and it also beats "second night at 50% off." And in both cases, the difference can be substantial. That's not to say that the "Better Tomorrow" promo isn't a great deal. It's just that you can probably do better—maybe even with a different deal at the same hotel.