Alaska Airlines offers $50 companion tickets once a year with their co-branded Visa ($99 companion ticket with the business Visa). This is probably the best companion ticket out there — it’s good on any fare, from cheapest in the market to first class, there are no blackout dates or other restrictions, and the companion ticket counts as the same booking class as the paid ticket. Earns miles, eligible for upgrades, etc.

USAirways offers $99 companion tickets once a year with their co-branded Visa. There are a few restrictions (such as minimum ticket price of the paid ticket, advance purchase requirements, even a few blackout dates) but in general it’s quite usable, and the companion ticket earns miles. In fact I used one for travel last weekend.

American’s Mastercard offers a companion ticket as well, but requires the paid ticket to be in a relatively high-priced booking class in addition to have a minimum ticket price. I tried to use one a couple times, price was always about the same as just buying two tickets outright. The certificate expired.

Then there are the standard travel promotion companion tickets that are nearly always next to worthless. They may require booking a full fare ticket (so the paid + free ticket likely cost more than two paid tickets). Lots of fees, restrictions. Whenever I see ‘free companion ticket’ or other such come-ons without lots of details, I’m skeptical.

So that’s how I started out when I heard American Express had introduced a new domestic companion ticket program for their Platinum and Centurion credit cards. They already offer a 2-for-1 deal on international business class with some carriers, and that requires purchase of a full fare business class ticket. It’s occasionally useful, but not too often.

This new program for domestic coach tickets turns out to have some uses.

Invite a travel companion to accompany you on your next flight. Receive complimentary companion airfare, up to four times each year, when you use your Platinum Card® to book qualifying domestic Coach-Class air travel – starting at $299 – aboard one of six major U.S. carrier. For more information or to make a reservation, call 1-866-354-8386 or the number on the back of your Card.

American, United, Continental, Delta, USAirways, and Northwest participate.

You have to pay $299 or more for the paid ticket (if the regular fare is, say, $249 you have to buy the $50 difference, and Hawaii airfares have a higher minimum – $899 from most airports, which divided by two may still be a good deal). Both tickets get charged a $15 ticketing fee, and they charge tax on the ‘free’ ticket.

There are a handful of blackout dates, but certainly not as bad as some (like what Amtrak does to their free tickets!).

The paid ticket should generally be eligible for elite benefits and mileage accrual. I don’t know yet about the companion ticket. But thus far it appears a worthwhile deal in some cases. It won’t always be a miracle worker, but it’s definitely one for the arsenal worth trying.