A checklist to remember when booking your next flight

What is most important to you? Best price, most comfortable seats, best schedule, accruing miles toward elite status or redeeming miles? Getting all of them on one ticket is as hard as drawing a straight flush.

‍Lowest published Business Class fares Like last year Continental has come out of the gate first with a Business Class sale to Europe. This year fares start at $1,488 round-trip—and only American, Lufthansa and United are matching at this point. (Fares for fall and winter travel are currently about $500 to $1,000 more.) However, many of the destinations offered by Continental are serviced with aircraft that don’t have its 170-degree reclining seats. See FCF Feb. 2006 and this link for more: http://www.continental.com/travel/inflight/businessfirst/default.asp

Lowest economy fares upgradeable to Business Class Even with the $500 mileage upgrade surcharge, American’s fares are often about the lowest you'll find, with United in the same ballpark. BA can also be very attractive, as its Premium Economy fares are often on sale (sometimes as low as $600) and can net you a nice upgrade to Business Class, and only require 25,000 BA miles, half the number many others charge. Don't have BA miles? You can buy them online in volume in conjunction with its Household Program for about $750 per round-trip upgrade. Delta's lowest upgradeable fares are usually in the $1,500 to $1,800 range. Instead, try to find a "heavily discounted" Business Class fare, usually around $2,100 to $2,600 (booked in I Class), for better seat availability and the right to earn the class-of-service bonus for both earned and elite qualifying miles. Continental's cash surcharge is confusing and expensive. Look for routes operated with 777s, as they have the 170-degree reclining seats, and go for its Z class fares. Don’t bother with Northwest, as you probably won't find any seats there.

B fare upgrades I like US Airways B-fare upgrade a lot. Philadelphia London costs as little as $628 and 20,000 miles round trip. American also has same great B fares, when upgrading to cities like Dublin. They require only 20,000 miles (30,000 less than normal) and there’s no $500 cash surcharge. Sample routes: Chicago Dublin's upgradeable B fare is only $1,018.

New airlines While EOS has reduced NY-London fares to $2,900 if you book 30 days in advance, MAXjet is the real deal: Everyday fares are in the $1,500 range and a recent airline e-newsletter (sign up for free at www.maxjet.com) offered promotional fares as low as $750.

Best First Class Getting a deal on a First Class seat isn't easy nowadays,if only because there are so few airlines on which three classes of service are offered, among them Air France, American, British Airways, Lufthansa, Malaysia Air, Singapore Airlines, SWISS and United. These carriers seem to be reducing the number of three-class routes, too. The best strategy is to use a 2-for-1 on routes where fares are disproportionately low (see below for examples). The only 2-for 1 programs to Europe are United via Ameniti.com; British Airways via the BA Visa Card (britishairways.com/travel/offerusvisa2for1), and SWISS via American Express International Airline Program (800) 443-7672.

Business Class 2-for-1s Unless you're flying on short notice, forget about two fers. There are very few routes on which a free companion ticket costs less than two deeply discounted Business Class fares with a 50- to 60-day advance purchase. For short-notice bookings, keep Iberia, a Oneworld carrier, in mind. It has its own free companion program and offers the lowest prices I've seen. More: (800) 772-4642.

Hidden Gems: Air New Zealand & Singapore Remember, Air New Zealand flies Los Angeles-London using aircraft fitted with the same seats you’ll find on Virgin Atlantic’s superlative Business Class. The flight can be booked using miles from Air Canada (an Amex Membership rewards partner) and United, both of them Air New Zealand mileage-program partners. This is simply one hot ticket. If you're flying from the West Coast to London, it pays to connect in LA.

Similarly, think of Singapore Airlines when flying New York-Frankfurt (Business Class seats on this route recline to flat). You can book this flight using miles earned on Singapore’s Star Alliance partners Air Canada and United, while Delta miles (available via Amex points transfer) can be used for both award and mileage upgrades.

When all else fails: Premium Economy Air New Zealand, British Airways, SAS, United and Virgin Atlantic offer a version of it, usually with about five or six inches more legroom. We usually find the lowest fares on BA starting in the $700 range round-trip from the Northeast, $1,200 from the West. United's Economy Plus seats can also be a good value, especially from the West Coast.

Final thoughts It’s easier to find one mileage award or upgrade seat than two, three, or four. If you find one, grab it and look for a deeply discounted fare for your companion instead of just moving on. You might also try to find flights into any European city if seats are not available to your first-choice destination, and buy a separate ticket to your final destination. EuorpeByAir.com has some of the best inter-Europe one-way fares. Children's fares: Some airlines (Continental, for example) do not offer them on discounted Biz Class fares, while many of the international carriers do discount, like BA and Virgin. Don't forget to compare, as the discounts can offset costs quite a bit.