At the risk of being accused of touting a particular credit card (in which I have no interest whatever), it's important to alert all cost-conscious travelers about the new (and rather innovative) Chase Card for United Airlines passengers. It costs $0 the first year, $95 the second year (thus $47.50 a year for the first two years), and primariy lets you and your travel companion each check a suitcase on a United Airlines flight without paying the $25 per suitcase fee each way. That means that both of you will save a total of $100 on a round-trip flight where you'll be checking a suitcase apiece. (This requires, of course, that you have used that particular credit card to pay for those United Airlines flights).
But wait, there's more. You'll also pay no 3% foreign transaction fee on credit card payments overseas, a nice extra saving of that outrageous sum that most avaricious credit cards charge. You'll enjoy priority boarding on United. You'll get two passes to enter and enjoy the United Club at your airport (or any other airport). And finally, you'll receive United frequent flyer mileage when you use the card to purchase United Airlines flights.
The valuable card is called the "United Plus Explorer", it's a Chase VISA Card, and you get one by phoning 888/744-6899 or by accessing TheExplorerCard.com. I think it's a major advance (that will obviously soon be emulated by other airline credit cards), and the savings can be quite substantial indeed.