If you haven't yet made your holiday travel plans, get busy.
Figure that the best days to start your Christmas trip will be Dec. 20, 21, 24, and 25, returning by Dec. 29. That's according to Northwest Airlines, which checked its prices and seat availability for the period and issued the results in a press release. Although Northwest didn't mention the New Year's weekend, I suspect that the best days will parallel those for the preceding week: Start your trip on Dec. 27, 28, or 31 or Jan. 1; return later that week.
But "saving money" isn't the only factor in your trip planning, and, overall, you might be better off paying more for your airfare if it gives you the time you really want at your destination.
Beyond its analysis of fares and availabilities, Northwest's annual checklist of holiday planning falls into the "round up the usual suspects" rubric: Fly on off-peak days, at off-peak times (very early morning, midday, or late) and Saturday evening; book early; shop around for the best deal; if you can't find a good deal to/from your most convenient airports, try alternative airports near your origin/destination; bring your own food; don't overpack; consider travel insurance if you buy a completely nonrefundable ticket or package.
Less obvious options also make sense, especially if you can't find a good deal through the usual shopping:
Consider one of the "opaque" services, Hotwire and Priceline. With Hotwire, you see a price but don't know the airline or schedule until after you "buy" your completely nonrefundable ticket; with Priceline, you set a price you're willing to pay, but, again, you won't know the airline or schedule until you buy. Those services may be your only option if you're trying to get a ticket on a giant airline less than 14 days in advance -- in those cases, you'll just have to accept the possibility of a lousy schedule.
Consider buying an air-hotel package, or -- if you're planning to stay with friends or relatives -- an air-car package. Sometimes, packagers still have cheap seats available when the airlines' own inventories of low-fare seats have already been sold.
Consider (this one is mine, not Northwest's) checking the last-minute agencies, especially if you're already too late to find a good advance-purchase deal. The big online sites operate last-minute programs, as do such specialized agencies as www.site59.com.
But finding the absolutely lowest airfare isn't always what you really want. Buying a more expensive ticket may improve your trip enough to warrant the extra cost. According to Northwest's calculations, for example, the average fare for a Thanksgiving trip on peak days -- leaving on Wednesday, returning next Sunday -- was $335. Switching one of the flights to an off-peak day cut that average by about $70.
Overall, you're already late for planning a holiday trip, and you'll probably have to accept some compromises: less-than-ideal schedules, higher-than-expected prices, or both. Chances are, however, if you're flexible, you can still get where you want to go.